DEGRADABLE ESCAPE MECHANISMS FOR POT GEAR:

A SUMMARY REPORT TO THE ALASKA BOARD OF FISHERIES

BY Gordon H. Kruse

and

A1 Kirnker

Regional Information Report No. 5593-01 Alaska Department of Fish & Game ~ivision of Commercial ~isheries

P.O. Box 25526 Juneau, Alaska 99802-5526

January 29, 1993

DEGRADABLE ESCAPE MECHANISMS FOR POT GEAR:

A SUMMARY REPORT TO THE ALASKA BOARD OF FISHERIES

BY Gordon H. Kruse

and

A1 Kimker

Regional Information ~eport' No. 5593-01 Alaska Department of Fish & Game Division of Commercial Fisheries

P.O. Box 25526 Juneau, Alaska 99802-5526

January 29, 1993

h he Regional Information Report Series was established in 1987 to provide an information access system for all unpublished divisional reports. . These reports frequently serve diverse ad hoc informational purposes or archive basic uninterpreted data. To accommodate timely reporting of recently collected information, reports in this series undergo only limited internal review and may contain preliminary data; this information may be subsequently finalized and published in the formal literature. Consequently, these reports should not be cited without prior approval of the author or the Division of Commercial Fisheries.

TABLE OF CONTENTS

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LISTOFTABLES . . . . . . . . . . . . . . . . . . . . . . . v

EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . 1

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . 3

GHOST FISHING: PROBLEM STATEMENT . . . . . . . . . . . . . 3

Overview . . . . . . . . . . . . . . . . . . . 3 Gear Loss . . . . . . . . . . . . . . . . . . . . . 4

Causes . . . . . . . . . . . . . . . . . . 4 Loss Rate in East Coast Fisheries . 4

. Loss Rate in West Coast Fisheries . . . . . . . 4 Loss Rate in Alaskan Fisheries . . . . . . . 4

~eterioration of Lost Pots . . . . . . . . . . . . . 5

Catch Rates of Lost Gear . . . . . . . . . . . . . 5

Ghost Fishing Effects on Crustaceans . . 6

Sublethal Effects . . . . . . . . . . . . . . . . 6

Lethal Effects . . . . . . . . . . . . . . . . . 6

Total Impacts of Ghost Fishing . . . . . . . . . . . . 7

American Lobsters . . . . . . . . . . . . 7 Dungeness Crabs . . . . . . . . . . . . . . . . 8

King and Tanner Crabs . . . . . . . . . . . . 8 Regulations to Deter Ghost Fishing . . . . . . . . . . 9

. . . . . ALTERNATIVE SOLUTIONS . . . . . . . . . . . 10 . . . . . ~lternative 1: Cotton Twine Only (Status Quo) 10

. . . . . . ~lternative 2: Ga1van.i~ Timed Release Only 10

Alternative 3: Cotton Twine or ~alvanic Timed Release . 10

Alternative 4: Galvanic Timed Release After Phase-in . 10

ANALYSIS OF ALTERNATIVES: ADVANTAGES AND DISADVANTAGES . 11

Cotton Twine Versus Galvanic Timed Releases . 11

Ease of Use 11 . . . . . . . . . . . . . . . . . . . ~eliability . . . . . . . . . . . . . . . . . 11 Compliance . . . . . . . . . . . . . . . . . . . . 12

Enforcement . . . . . . . . . . . . . . . . . . . Cost . . . . . . . . . . . . . . . . . . . . ., . Revenues . . . . . . . . . . . . . . . . . . . .

Comparison of Alternatives . . . . . . . . . . . . . .

CONCLUSIONS AND RECOMMENDATIONS . . . . . . . . . . : . . .

LITERATURECITED . . . . . . . . . . . . . . . . . . . .

APPENDIX 1: EXISTING REGULATION FOR POT ESCAPE MECHANISMS .

APPENDIX 2. DRAFT REGULATION REQUIRING GTRs ONLY . . . . .

APPENDIX 3 . DRAFT REGULATION REQUIRING COTTON TWINE OR GTRs

APPENDIX 4 . DRAFT REGULATION REQUIRING GTRs AFTER PHASE-IN

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12

Table

LIST OF TABLES

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Estimated cost per 250 pots and cost per pot for various galvanic timed release devices and cotton thread sizes. Sources and methods of cost. estimation appear in the text. . . . . . . . . . 19

EXECUTIVE SDMMARY

In Alaska, pots are commonly used in fisheries for crabs, spot shrimps and cod. Pots are lost from several causes, including: storms; strong tidal currents; shifting ice floes (snow crab fishery); gear abandonment; and pot buoys are sometimes cut by vessel traffic, entanglement with other gear, and occasional area disputes among fishermen.

Ghost fishing occurs when lost pots continue to catch crabs, fishes, and other animals. Ghost fishing causes a variety of sublethal and lethal effects. The former include carapace damage, appendage loss, and decrease in weight. Deaths are primarily due to cannibalism, predation, starvation, and suffocation in pots that are buried by sand.

Estimates of total crab mortality from ghost fishing are unavailaljle for Alaskan fisheries because of several unknowns: (1) rate of annual pot loss by fishery, (2) rate at which pots break down, (3) catch rates of lost gear, and (4) effects of entrapment on crabs. However, estimates of pot loss for two Alaskan fisheries (10% and 20%) are similar to loss rates (8-25%) for pot fisheries elsewhere where ghost fishing is significant. Also, recent laboratory studies and earlier field studies on Alaskan crab species suggest that ghost fishing has the potential to cause significant revenue loss to the fishing industry in Alaska. Undoubtedly, ghost fishing has been mitigated in recent years because of requirements for degradable escape mechanisms with cotton twine.

At the request of the Alaska Board of Fisheries at its March 1991 meeting, Alaska Department of Fish and Game (ADF&G) considered the merits of cotton twine versus galvanic timed release (GTR) mechanisms; i .e., a device composed of two stable metal eyelets and an active metal cylinder (magnesium allow) that corrodes in salt water. Specifically, we considered the advantages and disadvantages of the following four alternative regulations for degradable mechanisms in shellfish and groundfish pots: (1) cotton twine only (status quo), (2) GTR devices only, (3) cotton twine or GTRs at the prerogative of individual fisherman, and (4) only GTRs after some phase-in period during which either GTR and cotton twine are acceptable.

The main advantage of the cotton twine is its lower cost, whereas advantages of GTRs are reliability and ease of inspection. Disadvantages of twine are that breakage times are unpredictable and integrity of used twine is difficult to assess. A main disadvantage of GTRs is their cost relative to cotton twine.

Because of the shape of a GTR is much different than the appearance of cotton twine or pot webbing, regulations for GTRs are probably more enforceable than cotton twine. With twine the most difficult

part of enforcement is the ability to determine whether the twine is untreated cotton of appropriate thread size. With GTRs the most difficult part of enforcement is verification that the unit is designed to break within the mandated time rather than later.

Nevertheless, ADF&G strongly recommends degradable escape mechanisms, and breakage at 30 days seems optimal. However, longer average times for degradation of cotton thread (approximately 107 days for 60 thread in Dungeness crab pots and 89 days for 30 thread in all other pots) under current regulations reflects an attempt to achieve a sensible tradeoff between mean and variance of breakage time. That is, the reasoning by fishermen to favor 60 thread over 30 thread for Dungeness crab pots is based more on a desire to delay the time at which twines first begin to break and not so much a preference for a mean breakage time of 107 days rather than 89 days. Such a tradeoff between mean and variance in breakage times is unnecessary for GTRs that degrade at such a predictable rate.

Compared to pots laced with 30 or 60 thread, the 30-day GTR provides for increased crab survival associated with reduced periods of confinement in lost pots without the disadvantage of unexpected, premature breakage associated with smaller twine sizes. Although GTRs are more costly than cotton twine, these costs may be more than remunerated by increased revenues realized by fewer pots that lose their catches frompremature breakages of escape devices.

ADF&G supports alternative 4, in which GTRs are required after, say, a one-year phase-in period during which discretionary use of either GTRs or cotton twine is allowable. The phase-in period will provide opportunity for voluntary large scale testing of GTRs by industry and would facilitate a smooth transition to these new devices. Yet, in the unlikely event that some unforeseen problems create unsolvable obstacles during this phase-in period, then this GTR-only regulation could be modified. In this regard, ADF&G recommends that the BOF pre-schedule GTRs on its agenda for the spring 1994 meeting cycle. In revisiting this issue, the BOF would be afforded the opportunity to consider regulatory adjustments after hearing public testimony on GTR performance in Alaskan commercial pot fisheries.

INTRODUCTION

This report constitutes the last of a four part presentation by the Alaska Department of Fish and Game (ADF&G) and university of Alaska Fairbanks to the Alaska Board of Fisheries (BOF) at the king and Tanner crab meetings in Anchorage during February 2-10. 1993. The first part presented by A1 Kimker briefly recapitulates the history of regulations for escape mechanisms in shellfish and bottomfish pots.

Part 2 (Paul et al. 1993a) presented by Dr.. A. J. Paul characterizes the effectiveness of galvanic timed release (GTR) devices under various temperature and salinity conditions. A GTR is a device composed of an active metal cylinder (magnesium alloy) connecting two stable metal eyelets. The cylinder acts as an anode and the eyelets act as cathodes. The conductivity of salt water causes galvanic corrosion of the cylinder. When corrosion is complete, the eyelets separate completely.

Part 3 (Paul et al. 1993b) also presented by Dr. Paul investigates effects of starvation on the survival of red king crab (Para1 i t h o d e s c a m t s c h a t i c u s ) and Tanner crab ( C h i o n o e c e t e s b a i r d i . Starvation is one potential source of mortality experienced by crabs trapped in lost gear.

The purpose of this document is to (1) identify the problems associated with ghost fishing, (2) offer alternative solutions. (3) evaluate the advantages and disadvantages of the alternatives, and ( 4 ) suggest conclusions and ADF&G recomendations. Together with the other three reports, it is hoped that this four-part presentation provides information useful to BOF1s deliberations on proposals to change regulation 5 AAC 39.145 ESCAPE MECHANISM FOR SHELLFISH AND GROUNDFISH POTS.

GHOST FISHING: PROBLEM STATEMENT

Overview

In Alaska, pots are commonly used in fisheries for shrimps such as spot shrimp or prawn (Panda lus p l a t y c e r o s ) , and groundfish such as ~acif ic cod (Gadus m a c r o c e p h a l u s ) , and crabs. Ghost fishing occurs when pots lost from these fisheries continue to catch crabs, fishes, and other animals. Following terminology of Breen (1989). lost pots are untended pots capable of catching crabs or fish, whereas derelict pots are lost gear that have been damaged and can no 1onger.catch crabs or fishes.

Pots may become rebaited when captured animals die from starvation, lethal injuries associated with confinement, or other causes. Ghost fishing continues until an exit is provided by deterioration of the pot frame, sidewall or tunnel webbing, or a degradable

3

escape mechanism. Total impacts of ghost fishing on crab stocks and fisheries depend, in part, on the (1) rate of pot loss, (2) rate at which these pots deteriorate, (3) catch rates of lost gear, and (4) effects of confinement on crabs captured in lost pots. These are discussed in the following sections. Because data on Alaskan crab stocks are limited, examples from Pacific northwest stocks of Dungeness crabs and other crab and lobster species elsewhere are included where apropos.

Gear Loss

Causes. Gear loss occurs for a variety of reasons. Storms and strong tidal currents carry some pots to depths greater than the .

length of their surface lines. Pot buoys are accidentally cut by passing vessel traffic and sometimes deliberately cut by fishermen in local area disputes. Some are lost when buoy lines become entangled with other pots, longlines, and other fishing gear. In some instances, gear is simply abandoned by fishermen. In the Bering Sea snow crab (Chionoecetes opilio) fishery, buoys are sometimes severed or pots are displaced by rapid movements of ice floes driven by shifts in wind speed and direction. The ability of crab fishing vessels to reduce pot loss in this fishery is somewhat limited, because many vessels carry multiple deck loads of gear that are difficult to move quickly away from moving ice. Ice floes may advance more than 40 nautical miles in one day (W. Nippes, ADF&G, Kodiak, personal communication).

Loss Rate in East Coast Fisheries. A significant percentage (8- 25%) of pots may be lost each year from fisheries. For example, Miller (1977) estimated 8% annual pot loss of the snow crab fishery off Newfoundland. For the American lobster (Homarus americanus) fishery along the Maine coast, it was estimated that an average of 20-25% of all traps are lost annually (Sheldon and Dow 1975).

Loss Rate in West Coast Fisheries. For the Dungeness crab fishery along the Pacific coast, it is believed that annual loss of pots averages 10% (PMFC 1978), although in the Washington fishery it was estimated that 23% of pots were lost in the 1973-1974 season (Tegelberg 1974, as cited.in PMFC 1978) and that 18% were lost in 1975-1976 (Northup 1978, as cited in Muir et al. 1984). However, estimates of gear loss should be adjusted for thefts. For example, in the Dungeness crab fishery in the Fraser River estuary, Breen (1987) estimated that 11% of pots were lost each year, albeit 47% of these were thought to have been stolen.

Loss Rate in Alaskan Fisheries. In Alaska, ~ i g h and Worlund 11979) reported that fishermen generally felt that 10% of their pots wgre lost annually in the red king crab fishery during the 1970s. In 1991 based on skipper interviews (W. ~ippes, ADF&G, personal communication, ~odiak), it was estimated that 20% of all pots used in the Bering Sea/Aleutian Islands crab fisheries were lost. It

was suspected that most loss was due to ice movements during the snow crab fishery.

~eterioration of Lost Pots

In a simulated study of pot loss, Breen (1987) observed that Dungeness crab pots left in the water for 1 year still had frames, mesh and rubber lid straps in excellent condition. Dungeness crab pots believed to be lost for 4-5 years. were badly corroded and judged unfishable (Dahlstrom 1975 as cited in 'PMFC 1978) . , These two observations are consistent with results of a questionnaire conducted by Breen (1987) in which Dung.eness crab fishermen estimated that lost pots remained intact for an average of 2.2 years. On the other hand, it has been proposed that king crab pots may last 15 years (High and Worlund 1979), but there are no studies on the deterioration of pots used in king, Tanner and snow crab f.isheries in Alaska.

Catch Rates of Lost Gear

In general, catch rates are lower for lost gear than fished gear. Average catch rate of lost American lobster pots is about 10% of actively fished pots (Pecci et al. 1978). In the Fraser River estuary of British Columbia, actively fished Dungeness pots averaged 1.7 crabs per pot per day, whereas simulated lost pots caught an average of 16 crabs per pot per year. Catch rates of lost Dungeness crab pots at the end of the one-year study were as high as initial catch rates.

Although unbaited crab pots continue to catch crabs (Breen 19871, catch rates of lost pots may be affected by rebaiting. Fishes captured by crab pots include Pacific cod, Gadus macrocephalus and halibut, Hippogl o s s u s s t e n o l e p i s (High 1976 ; High and Worlund 1979). There is no question that death of these fishes in crab pots results in rebaiting of the pot.

Whether dead crabs serve as bait in crab pots is uncertain. Under experimental fishing, dead red king crabs did not attract live king crabs (High and Worlund 1979) and dead shore crabs ( C a r c i n u s maeanas) did not attract live crabs of another species, Cancer pagurus (Hancock 1974) . In fact, dead snow crabs, C h i o n o e c e t e s o p i l i o (Miller 1977) and spiny lobsters, P a n u l i r u s cygnus (Hancock 1974) repelled members of the same species. In general, softshell crabs are well known to be cannibalized, but whether newly molted crabs in pots act as bait is unknown.

Ghost Fishins Effects on Crustaceans

Sublethal Effects. Ghost fishing causes a variety of sublethal and lethal effects. Sublethal effects include (1) carapace damage, (2) appendage loss, and (3) decrease in weight. Dahlstrom (1975) found that 83% of Dungeness crabs recovered from lost pots had bacterial or fungal pitting on the carapace. In simulated lost pots, Muir et al. (1984) found that nearly all Dungeness crabs lost weight over a 28-day period; those confined the longest lost the greatest weight.

In a study of the effects of ghost fishing on American lobsters, Pecci et al. (1978) estimated that 28% of captured lobsters had injuries, and many injuries were attributed to aggressive encounters with other lobsters in the pot. In a similar field experiment, nearly all legal-sized Tanner crabs lost limbs after 119 days of capture, but cause of limb loss was not established (Kimker 1992). Cause is indisputable in a controlled laboratory experiment with Tanner crabs starved for 210 days: 30% of crabs had limbs eaten by their tank companions (Paul et al. 1993b) . Lost limbs can be regenerated, although young adult crabs may take 4-7 years for full limb restoration (Edwards 1972).

Lethal Effects. Deaths from ghost fishing are due to (1) pots that get washed ashore during storms (Sheldon and Dow 1975), ( 2 ) suffocation in pots that are buried by sand (High 19761, (3) cannibalism, (4) predation, and (5) starvation. Sheldon and Dow (1975) estimated that 18% of American lobsters captured in lost pots were cannibalized. For this reason, mortality in lost pots was higher in summer during molting. Likewise, Dahlstrom (1975) found cannibalized crabs in lost Dungeness pots recovered in California. In the laboratory, 10% of Tanner crabs starved over a 210-day period were cannibalized, whereas 83% of so£ tshell red king crabs starved over a 175-day period were cannibalized (Paul et all 199333). Undoubtedly, the higher rate for red king crabs was largely due to their soft shell condition.

Predation by octopuses (Dolfl eini do1 fleini) on trapped Dungeness crabs has been observed (High 1976) . Also, ~ecci et al. (1978) found that pots with black sea bass (~entropristis striata) had high' numbers of dead American lobsters, although the reason for this association was not known. Fishermen have observed that halibut often enter pots and are quickly killed by predatory amphipods (High and Worlund 1979), and the same may be true of crabs in some Alaskan locations (Kimker 1992).

Crabs have limited abilities to withstand starvation. Under controlled laboratory conditions, the length of the starvation period was related to mortality rate (Paul et al. 1993b) . After 30, 60, 90, and 120 days of starvation, 60%, 40%, 100% and 100% of Tanner crabs later died even though many of them lived through the starvation period and were then fed freely over the balance of the

230-day observation period. Likewise, for softshell red king crabs, survival over a 175-day period was 12% after 30 days of starvation and 0% after 60 days of starvation. However, survival of continuously fed crabs was only 25%; thus, the overall low survival rates of red king crabs were likely due to injuries and their softshell condition (Paul et al. 1993b).

Results of two earlier studies on red king crabs and Dungeness crabs are consistent with the delayed mortality of starved crabs found by Paul et al. (1993b) . In one of these, High and Worlund (1979) found that tag recovery rates (2.3% for sublegals and 17.5% for legals) of red king crabs confined for 10-16 days in simulated lost pots was significantly (P<O-.05) lower than those confiried in pots for only 1-4 days (31.4% and 33.1%, respectively) before release and to those released after 2 days in a live tank (34.9% and 35.2%).

In the other study, High (1976) found that during the first 4 weeks of confinement Dungeness crabs became agitated when approached by divers, but that subsequently, crabs had to be prodded to determine that they were still alive. Although survival (or tag recovery) rates of Dungeness crabs were not studied in this case, laboratory experiments are currently underway to determine starvation effects on survival of Dungeness crabs (Paul et al:1993b).

At sea, crabs captured by lost pots may not be totally deprived of food. Pecci et al. (1978) documented catches of other species of fish and invertebrates by lost lobster pots. Presumably, at least some of these catches could serve as prey for trapped lobsters. Breen (1987) found visual evidence of feeding by Dungeness crabs in experimental lost pots. Trapped Dungeness crabs dig bivalves from the substrate under the pot, and animals such as hermit crabs (Pagurus), squid (Loligo opalescens) and univalves may be captured by crabs after they stray into the pot.

Total Impacts of Ghost Fishinq

Impacts of ghost fishing on crab stocks and fisheries is a function of total removals due to death or permanent confinement. Mortality and escape rates have been estimated for a number of fisheries, but estimates of total losses are available for only a few crustacean fisheries worldwide.

American Lobsters. Pecci et al. (1978) estimated that escapement from intact pots was only 1%; 25% of all trapped lobsters were found dead during a 2-year study. Sheldon and Dow (1975) had estimated a higher rate of escapement but the same mortality rate; 18% of American lobsters captured in lost pots were cannibalized and another 25% did not escape the trap. Sheldon and Dow estimated that 200,000 of approximately 1 million lobster pots were lost annually in the Maine fishery. Smolowitz (1978) estimated that the

ghost fishing catch in the domestic American lobster fishery in 1978 was 1.5 million pounds worth $2.5 million (U.S.).

D u n g e n e s s C r a b s . In two studies of simulated lost Dungeness crab pots with functional triggers and escape rings, High (1976) found a 17% mortality rate for crabs confined for 12 days, and Muir et al. (1984) found that 19% of crabs died when confined for 28 days. In the first study, escape rates were 77% for sublegal males, and 45% of small legal-sized males. In the second st.udy, 66% of sublegal males and 49% of small legal males escaped. High (1976) speculated that apparent escapement rates may have been influenced by octopuses that frequented the pots. In pots with .functional triggers and escape rings closed, 79% of legal males and 33% of sublegal males did not escape after 74 days.

In a study of simulated lost pots in British Columbia, 49% of sublegal crabs and 52% of legal crabs died (Breen 1987). Half of all deaths observed over 1 year of confinement occurred during the first 50 days. For 1984, Breen (1987) estimated a loss of approximately 2,800 out of a total of 26,000 pots in the Dungeness crab fishery in the Fraser River estuary. Further, he estimated the catch from lost pots to be 7% of the annual Dungeness crab harvest in British Columbia or. 46,000 pounds worth $83,000 (Canadian) at $1.80/lb (Canadian).

K i n g a n d Tanner C r a b s . Paul et al. (1993b) found very low (<12%) survival rates for softshell red king crabs, but poor condition of experimental crabs makes it difficult to extend these results to the fishery. High and Worlund (1979) estimated that an average of 8% of large sublegal red king crabs and 20% of small legal red king crabs did not escape from lost pots over a 16-day period. Much lower tag recovery rates of crabs held for just 10-16 days compared to shorter periods of confinement indicated that significant mortality occurred after the crabs were released. Based on this finding, they pointed out that any procedure that permitted quick escape from pots would reintroduce healthier crabs into the fishable stocks.

Depending on the length of the starvation period, 40-100% of Tanner crabs died over a 230-day period in the laboratory (Paul et al. 1993b). In simulated lost pots at sea, 39% of legal-sized Tanner crabs died within 119 days (Kimker 1992). The first mortalities occurred after only 14 days of confinement.

Pot loss in the Bering Sea can be estimated, if we are willing to make an assumption about pot loss rates. For example, in the red king crab-fishery in Bristol Bay alone, approximately 68,000 pots were registered in 1990 and 90,000 were registered in 1991 (Griffin and Ward 1992). If we assume that the 20% loss rate estimated for 1991 (W. Nippes, ADF&G, personal communication, Kodiak) is also representative of 1990, then approximately 31,600 pots were lost during 1990-1991 combined.

Estimation of total crab mortality from this lost gear is not possible because of several unknowns: ghost fishing catch rates, life span of lost pots, and cumulative effects of confinement on red king crab survival. Legal king crabs weighed an average of 6.5 pounds in 1992 and a typical price in recent years was $5 .OO per pound (Griffin and Ward 1992). Thus, if even one legal king crab was killed by each pot lost during 1990-1991, then annual loss would be 31,600 legal crabs with a combined weight of 205,400 pounds, and a value of $1 million.

True crab loss by lost pots would be partly mitigated by several factors: (1) the existing biodegradable twine regulation (ADF&G 1992, Appendix 1) that is designed to provide, exit from lost pots, (2) some portion of lost pots become derelict -- do not ghost fish because they are non-functional, (3) some pots considered "lost" may have actually been stolen, and (4) pot loss rates for 1990 may have been lower than for 1991.

On the other hand, several factors may act to intensify ghost fishing effects: (1) High and Worlund's (1979) study indicates that confinement for as little as 10-16 days increases crab mortality, so that existing biodegradable twine regulations may not minimize ghost fishing mortality, (2) lost pots may capture many crabs, for instance an average of 9.3 Dungeness crabs may be killed by each lost pot per year (Breen 1987) , (3 ) given the durability of king crab pots (High and Worlund 1979) , it is likely that some pots lost prior to 1990 continue to ghost fish, and ( 4 ) lost pots in the Bering Sea capture other commercially important species, such as Tanner crab, snow crab, and Pacific halibut. Clearly, ghost fishing is a subject that deserves more attention, given the value of crab fisheries in Alaska.

Requlations to Deter Ghost Fishinq

Although it appears that GTRs are not required for any pot fisheries worldwide, they have been considered for the sablefish fishery along the coast of British ~olumbia (Scarsbrook et al. 1988), the Dungeness crab fishery along the pacific northwest coast, and the snow crab fishery along the ~tlantic coast of Canada. Alaska requires degradable devices with 60 thread cotton twine for Dungeness crab fisheries and 30 thread cotton twine for other crab fisheries (ADF&G 1992; Appendix 1). Cotton twine of size 120 thread is required for Dungeness crab fisheries from California to British Columbia. For the sablefish fishery of British Columbia, a strand of untreated natural fiber not larger than 2 mm -in diameter is required (Scarsbrook et al. 1988) . For the U.S. Atlantic lobster fishery, the "ghost panel" can be fastened by untreated natural twine no greater than 4.8 mm in diameter or uncoated ferrous metal wire no greater than 2.4 mrn in diameter. Wooden lobster pots are considered "degradable" and are exempt from the regulation.

ALTERNATIVE SOLUTIONS

Several alternatives are available to address the ghost fishing problem in Alaska. Four were selected for analysis.

Alternative 1: Cotton Twine Only (Status Quo)

Current regulation 5 AAC 39.145 ESCAPE MECHANISM FOR SHELLFISH AND BOTTOMFISH POTS (ADF&G 1992; Appendix 1) specifies that a sidewall of all shellfish and bottomfish pots must contain an opening equal to or exceeding 18 inches (6 inches for shrimp pots) in length that must be laced by a single length of untreated, 100% cotton twine no larger than 30 thread knotted at each end only. The opening must be within 6 inches of the bottom of the pot and parallel with it. As an alternative, for Dungeness crab pots, the pot lid tie-down straps may be secured to the pot at one end by a single loop of untreated, 100% cotton twine no larger than 60 thread. This regulation was adopted by the BOF in March 1990 and the current 60- thread requirement was changed from 30-thread for Dungeness crab pots in March 1991.

Alternative 2: Galvanic Timed Release Only

An alternative to the current biodegradable mechanism (untreated cotton twine, alternative 1) is the GTR. A draft regulation (~ppendix 2 ) that mandates the use of a GTR specifies an opening similar to that now required, except that the opening is laced with 36 thread twine of any composition that is fastened to a GTR designed to corrode in 30 days or less.

Alternative 3: Cotton Twine or Galvanic Timed Release

The third alternative is a blend of alternative 1 and 2. Under this alternative, a draft regulation (Appendix 31 modifies the existing regulation to permit the use of GTRs as an option. The choice of degradable mechanisms would be the discretion of individual fisherman.

Alternative 4: Galvanic Timed Release After phase-in period

The fourth alternative is a blend of alternative 2 and 3. Under this alternative, a draft regulation (Appendix 4 ) modifies the existing regulation to permit the optional use of GTRs or cotton twine through June 30, 1994. Then, comencing July 1, 1994, only GTRs could be used as the pot degradable escape mechanism.

ANALYSIS OF THE ALTERNATIVES: ADVANTAGES AND DISADVANTAGES

Cotton Twine Versus Galvanic Timed Release

Ease of Use. Both GTRs and cotton twine are rather easy to use. However, it is anticipated that replacement of GTRs is likely to be easiest and quickest. Given the reliability of GTR breakage times (see below), replacement dates can be pre-scheduled when most convenient to skipper and crew. Unplanned breakage is not likely to occur once fishermen become familiar with GTR breakage schedules. Because release time can be anticipated based .on the size of the device, it is very easy for a fisherman to.inspect't.he condition of the GTR.

GTRs may cause some initial difficulty among enforcement officers and fishery managers. Because the specific metal alloy recipe of GTRs may vary among manufacturers, each model may have to be tested separately to determine breakage times under Alaskan environmental conditions. However, after initial verification of performance, no further testing would be required and each unit would be pre- approved for future use.

~eliability. Cotton twine was tested during a simulated king crab fishing experiment in lower Cook Inlet (Kimker 1990). Mean (and range in parentheses) of breakage time were: 89 (50-106) days for 30 thread; 101 (57-119) days for 42 thread, and 107 (57-139) days for 60 thread. During commercial fishing operations, breakage times of cotton twine can become quite unreliable. Exposure of cotton twine to the damp environment while stowed aboard fishing vessels promotes degradation that can lead to premature breakage when later tied to the pot.

Studies of GTRs show that breakage times are predictable and accurate; unplanned releases are very unlikely. GTRs were tested on conical snow crab pots on fishing grounds in the Northwest Atlantic Ocean (Gagnon and Boudreau 1991) . GTRs were placed in snow crab pots and inspected after deployment for 20, 43, 53, 60, 77 and 82 days. For a unit designed to break at 50 days, none broke by day 43, 44% broke by day 53, and 100% had released by day 60. For a 75-day GTR, none broke by day 67, 57% broke by day 77, and 83% released by day 82. For the 100-day unit, none broke by day 82 when sea trials were completed.

GTRs designed for 75-day and 100-day breakage were tested on several commercial fishing vessels during the snow crab fishery in 1991 in the Northwest Atlantic Ocean (Boudreau 1991). No devices broke due.to corrosion during the commercial fishing season which lasted up to 43 days depending on management unit. Less than 1% of the units broke during fishing operations presumably due to impacts while arranging gear on deck. In all cases, breakage occurred at the point where the eyelet contacts the cylinder.

Recently, GTRs were also tested under various temperature and salinity conditions in Alaska (Paul et al. 1993a) . Tests were conducted on GTRs designed for a specific breakage time and similar units that were slightly larger and slightly smaller. In most trials, at least one test model of GTR released within 2-3 days of the date specified by the manufacturer. Paul et al. (1993a) found linear relationships between GTR size and day of release. This is consistent with the findings of Gagnon and Boudreau (1991) and Boudreau (1991) that the change in weight of GTRs through time decreases linearly with the number of days immersed in sea water.

Compliance. It is expected that compliance with GTR regulations would be greater than with cotton twine regulations. As just discussed, cotton twine and GTR regulations can be developed that specify very similar mean breakage times to meet conservation objectives. However, the variance in breakage times is much higher for cotton twine. A mechanism that breaks too soon causes loss of crab catches. Thus, there will be motivation to use twine with mean breakage times greater than stipulated, so that escape is not provided in any pots while fishing. This could be accomplished by using heavier twine than authorized or by using a twine made of cotton-synthetic blended fibers to slow degradation.

Because unplanned breakage of GTRs will be rare with good record- keeping and experience, it unlikely that unplanned breakage will diminish compliance with GTR regulations. However, there will be economic incentives to use GTRs that break longer than regulated: GTRs that take twice as long to break do not cost twice as much.

Enforcement. It is easier to establish whether a pot has a GTR than whether it has cotton twine. Once a GTR is used, degradation occurs. Whether the GTR is new or old, a simple test to determine whether the unit is a GTR is to just place it in sea water. Upon contact, the GTR begins to bubble.

Determination of twine composition is more difficult. Synthetic fibers add to the strength of twine and impede degradation. The presence of synthetic fibers are evident under microscopic inspection; a twine composed of a blend of cotton and synthetic fibers has inconsistencies in the fiber structures observed. When burned, synthetic fiber leaves a hard residue unlike cotton twine. However, burning requires the twine to be dry -- thus adding to the difficulty of enforcement.

With GTRs the most difficult part of enforcement is to determine that the unit is designed to break within the mandated time and not some other (longer) time. Manufacturers can make GTRs that break at any desired time under any specified temperature and salinity conditions. Because breakdown of the GTR is a chemical reaction, higher temperatures and higher salinities cause quicker degradation. Therefore, GTRs designed to break down in 30 days for the Gulf of Mexico will take longer than 30 days to break in the

Gulf of Alaska. The only way to determine true breakage time for a GTR of unknown design is to test it under certain temperature and salinity conditions. Thus, while it is easy to determine compliance with GTR usage, it is more difficult to determine that the GTR in use meets breakage time requirements.

Costs. Costs of installation were estimated for GTRs and cotton twine (Table 1). GTR costs were provided by Mr. Ed Wyman of Neptune Marine Products. Costs of cotton twine were provided by Seattle Marine and Fishing Supply Company. For twine, cost per pound was $4.83, and lengths per pound'were: 610 feet for 30 thread; 315 feet for 60 thread; and 155 feet for 120 thread. Costs of lacing pots with cotton twine-assumed an average of 3 feet per pot.

Revenues. There is no evidence that the presence of cotton twine or GTRs influence catches. Among cotton twines of sizes 30, 42, and 60 thread, there was no difference in average catches of red king crab, Tanner crab, Pacific cod, nor Pacific halibut in simulated fishing experiments in lower Cook Inlet (Kimker 1990). Likewise, fishing experiments in the Atlantic snow crab fishery showed that presence of GTRs had no effect on pot catches (Boudreau 1991). It has also been the experience of one of us ( A . K . ) that use of GTRs has had no effect on catches during pot surveys for king and Tanner.crabs in lower Cook Inlet.

Lost revenue may occur from premature, unanticipated breakage of degradable devices. Because of a GTR's greater reliability, this is much less likely to occur with GTR-equipped pots. Because of the broader range of twine breakage times (Kimker 1990), lost revenues associated with escaped crabs is more likely to occur with pots equipped with cotton twine.

Ghost fishing causes lost fisheries revenues due to mortality of entrapped crabs and fishes. Starvation studies (Paul et al. 1993b) and field experiments (Breen 1987, ~ i g h and Worlund 1979) indicate that confinement of crabs for periods likely to be experienced under current regulations will cause some mortality. Crab mortality could be markedly reduced, if GTRs were required with a shorter mean breakage time (say, 30 days) than experienced by cotton twine under current regulations (89 days for 30 thread and 107 days for 60 thread). However, it is not possible to quantify this savings without detailed information on likely twine and GTR replacement schedules during commercial fisheries and crab mortality rates which vary seasonally under varying lengths of confinement in lost pots at sea.

Comparison of Alternatives

Each alternative seems reasonable. ~lternative 1 (status quo) provides for escape from pots after an average of 89 days for 30

thread and 107 days for 60 thread. These breakage times are not ideal in terms of conservation of crab resources, but on the other hand smaller threads may lead to an unacceptable rate of premature twine breakage and lost catches. For example, reasoning by fishermen to favor 60 thread over 30 thread in Dungeness crab pots is based more on a desire to delay the time at which twines first begin to break and less on a preference for a mean breakage time of 107 days rather than 89 days.

Alternatives 2, 3, and 4 that include GTRs permit the specification of a shorter mean breakage time (say, 30 days) than experienced by cotton twine under current regulations. Thus, if GTRs are used by fishermen, then crab mortality caused by lost pots would be reduced by some significant (albeit, non-quantifiable) amount.

It would seem that alternative 3 (optional use of cotton twine or GTRs) is much more preferable to alternative 1 (cotton twine only) , because i't provides for some reduction in crab mortality associated with the loss of pots rigged with GTRs as compared to lost pots equipped with cotton twine. Also, it gives fishermen the option to select either twine or GTRs based on their personal financial assessment. That is, alternative 3 would not mandate higher operational costs, but would function through economic incentives.

Alternative 2 (GTRs only) provides the greatest potential for resource conservation. In as much as GTRs cost significantly more than cotton twine, alternative 2 imposes the greatest costs on the industry. Yet, GTR expenditures are rather small relative to overall expenses of fishing. Further, the increased cost for GTRs may be more than offset by receipts from increased catches.

For example, a fisherman using 250 pots during the red king crab fishery in Bristol Bay would pay approximately $369 more to outfit the pots with 30-day GTRs than with 30-thread cotton twine. However, it is important to note that, for example, at $5 per pound exvessel, one 8 pound red king crab is worth $40. If just one crab pot with cotton twine broke prematurely and 9 legal king crabs had escaped, these lost revenues would have paid for the increased costs of GTRs for all 250 pots. Because, mean catch rates in the Bristol Bay fishery was 12 crabs worth an average of $480 per pot in 1991, it seems that there is significant potential for positive net economic benefits from GTRs usage -- at least for this crab fishery . For comparison, the Tanner and snow crab fisheries of the ~ering Sea were considered. In the Tanner crab fishery in 1991-1992, mean catch per'pot was 21, mean weight of legal crabs was 2.5 pounds, and average price was $1.50 per pound r riff in and Ward 1992). Thus, an average pot caught Tanner crabs worth $78.75. In the snow crab fishery in 1991, mean catch per pot was 188, average weight was 1.2, and price averaged $0.50 (Griffin and Ward 1992). Consequently, an average pot in this fishery caught $112.80 worth

of crabs. Therefore, positive net economic benefits would accrue to a vessel fishing 250 pots equipped with GTRs (as opposed to cotton twine), if at least 3 (snow crab fishery) or 5 (Tanner crab fishery) pots would have lost their crab catches due to twine failures. Note, however, that this simple assessment does not include the future value of crabs afforded timely escape from lost gear equipped with GTRs.

Alternative 4 (GTRs after phase-in period) provides some of the advantages of both alternative 2 and alternative 3. The initial phase-in period provides a 1-year period of discretionary use of GTRs or cotton twine. The phase-in period would provide the opportunity for voluntary large scale testing of GTRs by fishermen in cooperation with ADF&G to facilitate a smooth transition to these new devices. Because GTR usage would not be mandatory during the transition, unanticipated problems could be resolved in an judicious manner with the cooperation of industry, managers, scientists and enforcement officers. Yet, after one year of successful performance, mandatory use of GTRs would achieve the same potential for resource conservation as under alternative 2.

CONCLUSIONS AND RECOMMENDATIONS

Degradable mechanisms are important for resource conservation and produce economic benefits. Laboratory studies suggest that most king and Tanner crabs die if starved for more than 30 days. Ability of trapped crabs in lost pots to capture some prey may partially mitigate this starvation effect. However, field studies have shown that lost pots can cause significant crab mortalities. Simulated lost pots each killed nine Dungeness crabs per year in an area of rather low crab density in the Fraser River estuary of British Columbia. In lower Cook Inlet, Alaska, simulated lost pots killed 39% of entrapped Tanner crabs within 119 days. Also, significantly reduced-tag recovery rates implies lower survival of red king crabs confined in simulated lost pots after only 10-16 days compared to those confined 1-4 days. These observations underscore the need to afford trapped crabs a timely escape from lost pot gear.

Both cotton twine and GTRs are practical as degradable escape mechanisms, and there are advantages and disadvantages to both. The main advantage of the cotton twine is its lower cost, whereas advantages of the GTRs are reliability and ease of inspection. Disadvantages of twine are that breakage times are unpredictable and integrity of used twine is difficult to assess. A main disadvantage of the GTR is its cost relative to cotton twine.

Because cotton twine is not nearly as distinguishable from pot webbing as is a GTR, regulations for GTRs are probably more enforceable than those for cotton twine. With twine the most difficult part of enforcement is to determine whether the twine is

untreated 100% cotton of appropriate thread size. with GTRs the most difficult part of enforcement is to determine that the unit is designed to break within the mandated time and not some other ( longer) time . Regardless, ADF&G strongly recommends continued requirements for degradable escape mechanisms in pot gear; breakage at 30 days seems optimal. Therefore, ADF&G recommends legalization of the 30-day GTR. Current regulations, which provide for longer average times for degradation of cotton thread (approximately 107 days for 60 thread in Dungeness crab pots and 89 days for 30 thread in all other pots), reflect an attempt to achieve a sensible tradecff between mean and variance of breakage time., This tradeoff is not necessary with the GTR which degrades at a very predictable rate.

Compared to pots laced with 30 or 60 thread, the 30-day GTR provides for increased crab survival associated with reduced periods of confinement in lost pots without the disadvantage of unexpected, premature breakage associated with smaller twine sizes. GTRs are more costly than cotton twine, but these costs may be remunerated by increased revenues. That is, with GTRs, it is anticipated that fewer pots will lose their catches of crabs due to premature breakage of escape devices. There is significant potential for positive net economic benefits associated with a switch from cotton twine to GTRs, but data necessary to make quantitative assessments are unavailable.

ADF&G favors alternative 4, in which GTRs are required after a transition period during which discretionary use of either GTRs or cotton twine is allowable. This phase-in period would provide opportunity for voluntary large scale testing of GTRs by industry and would facilitate a smooth transition to these new devices. Yet, in the unlikely event that some unforeseen problems create unsolvable obstacles during this phase-in period, then this GTR- only regulation could be modified. In this regard, ADF&G recommends that the BOF pre-schedule GTRs on its agenda for the spring 1994 meeting cycle. In revisiting this issue, the BOF would be afforded the opportunity to consider regulatory adjustments after hearing public testimony on GTR performance in Alaskan commercial pot fisheries.

LITERATURE CITED

ADF&G (Alaska Department of Fish and Game). 1992. Commercial shellfish regulations, 1991. Alaska Department of Fish and Game; Division of Commercial Fisheries, Juneau.

Boudreau, M. 1991. Use of a galvanic time release mechanism on crab traps during the 1991 snow crab fishing season. Federal program for Fisheries Development of Quebec, Report 3006, Quebec City.

Breen, P.A. 1987. ~ortality of Dungeness crabs caused by lost traps in the Fraser River estuary, British Columbia. North American Journal of Fisheries Management 7:429-435.

Breen, P . A . 1989. A review of ghost fishing by traps and gillnets. Pages 571-599 in Proceedings of the second international conference on marine debris. ~ational Marine ~isheries Service, Southwest Fisheries Science Center, Honolulu, Hawaii.

Dahlstrom, W.A. 1975. Summary of information on recovered lost .

traps. California Department of Fish and Game, Marine Research Region, Processed Report.

Edwards, J.S. 1972. Limb loss and regeneration in two crabs: the king crab Para1 i thodes camtschati ca and the Tanner crab Chionoecetes bairdi. Acta Zoologica 53: 105-112.

Gagnon, M., and M. Boudreau. 1991. Sea trials of a galvanic corrosion delayed release mechanism for snow crab traps. Canadian Technical Report of Fisheries and Aquatic Sciences 1803, Quebec City.

Griffin, K.L., and M.L. Ward. 1992. Annual.management report for the shellfish fisheries of the Bering Sea area, 1992. Pages 151-197 Annual management report for the shellfish fisheries of the westward region, 1991. Alaska Department of Fish and Game. Division of Commercial Fisheries, Regional Information Report 4K92-9, Kodiak.

Hancock, D . A . 1974. Attraction and avoidance in marine invertebrates - their possible role in developing artificial bait. Journal du Conseil 35: 328-331.

High, W . L . 1976. Escape of Dungeness crabs from pots. Marine Fisheries Review 38 (4) : 19-23.

High, W.L., and D.D. Worlund. 1979. Escape of king crab, Paralithodes camtschatica, from derelict pots. National Marine Fisheries Service, NOAA Technical Report NMFS SSRF-734.

Kirnker, A. 1990. Biodegradable twine.report to the Alaska Board of ~isheries. Alaska Department of Fish and Game, Division of Commercial Fisheries, Regional Information Report 2H90-05, Anchorage.

Kimker, A, 1992. Tanner crab survival in closed pots. Alaska Department of Fish and Game, ~ivision of commercial FisheriGs, Regional Information Report 2A92-21, Anchorage.

Miller, R.J. 1977. Resource underutilization in a spider crab industry. Fisheries 2(3): 9-13.

17

~ u i r , W.D., J. T. Durkin, T.C. Coley, and G. T. McCabe, Jr. 1984. Escape of captured Dungeness crabs from commercial crab pots in the Columbia River estuary. North ~rnerican Journal of ~isheries Management 4: 552-555.

Northup, T. 1978. Development of management information for coastal Dungeness crab fishery. Washington Department of Fisheries, project Completion Report 1-114-R, ~lympia.

PMFC (Pacific Marine Fisheries Commission). 1978. Dungeness crab project of the state-federal fisheries management program. pacific Marine Fisheries Commission, Portland, Oregon.

Paul, J.M., A.J. Paul, and A. Kimker. 1993a. Tests of galvanic release for escape devices in crab pots. Alaska Department of Fish and Game, Division of Commercial Fisheries, Regional Information Report 2A93-02, Anchorage.

Paul, J.M., A.J. Paul, and A. Kimker. 1993b. Starvation resistance in Alaskan crabs: interim report. Alaska Department of Fish and Game, Division of Commercial Fisheries, Regional Information Report 2193-03, Anchorage.

Pecci, K . J . . R.A. Cooper, C.D. Newell, R.A. Clifford, and R.J. ~molowitz. 1978. Ghost fishing of vented and unvented lobster, Homarus arnericanus, traps. Marine Fisheries Review 40 (5-6) : 9-43.

Scarsbrook, J.R., G.A. McFarlane, and W. Shaw. 1988. Effectiveness of experimental escape mechanisms in sablefish traps. North American Journal of Fisheries Management 8: 158- 161.

Sheldon, W.W., and R.L. Dow. 1975. Trap contributions to losses in the American lobster fishery. Fishery Bulletin 73: 449- 451.

Smolowitz, R.J. 1978. Trap design and ghost fishing: discussion. Marine Fisheries Review 40(5-6):59-67.

Tegelberg, H.C. 1974. Coastal Dungeness crab study. Washington Department of Fisheries, Commercial ~isheries Research and Development Act, Project 1-92R, Annual Report for July 1, 1973 to June 30, 1974.

Table 1. Estimated cost per 250 pots and cost per pot for various galvanic timed release devices and cotton thread sizes. Sources and methods of cost estimation appear in tne text.

a. Galvanic Timed Release

GTR Type Cost/Pot Cost/250 Pots

14 .day $1.20 30 day $1.50 45 day $1.65

b. Cotton Twine

, Thread Size Cost/Pot . Cost/250 Pots

APPENDIX 1. EXISTING REGULATION FOR POT ESCAPE MECHANISMS

5 AAC 39.145. ESCAPE MECHANISM FOR SHELLFISH AND BOTTOMFISH POTS. A sidewall, which may include the tunnel, of all shellfish and bottomfish pots must contain an opening equal to or exceeding 18 inches in length, except in shrimp pots the opening must be a minimum of six inches in length. The opening must be laced, sewn, or secured together by a single length of untreated, 100 percent cotton twine no larger than 30 thread. The cotton twine may be knotted at each end only. The opening must be within six inches of the bottom of the pot and must be parallel with it. The cotton twine may not be tied or looped around the web bars. Dungeness crab pots may have the pot lid tie-down straps secured to the pot at one end by a single loop of untreated, 100 percent cotton twine no larger than 60 thread, as a substitute for the above requirements; the pot lid must be secured so that when the twine degrades, the lid will no longer be securely closed.

APPENDIX 2. DRAFT REGULATION FOR POT ESCAPE MECHANISMS: GALVANIC TIMED RELEASE DEVICES ONLY

5 AAC 39.145. ESCAPE MECHANISM FOR SHELLFISH AND BOTTOMFISH POTS. A sidewall, which may include the tunnel, of all shellfish and bottomfish pots must contain an opening equal to or exceeding 18 inches in length, except in shrimp pots the opening must be a minimum of six inches in length. The opening must be laced, sewn, or secured together by a single length of treated or untreated twine no larger than 36 thread. A galvanic timed release (GTR) device designed to completely corrode in no more than 30 days in salt water must be integral to the length of twine so that when the GTR completely degrades the twine will no longer be securely attached to the web of the pot. The twine may be knotted at each end and at the attachment points to the GTR only. The opening must be within six inches of the bottom of the pot and must be parallel with it. The twine may not be tied or looped around the web bars. As a substitute for the above requirements, Dungeness crab pots may have the pot lid tie-down straps secured to the pot at one end by a single length of treated or untreated twine no larger than 36 thread. A galvanic timed release (GTR) device designed to completely corrode in no more than 30 days in salt water must be integral to the length of twine. The pot lid must be secured so that when the GTR completely degrades, the lid will no longer be securely closed.

APPENDIX 3. DRAFT REGULATION FOR POT ESCAPE MECHANISMS: COTTON TWINE OR GALVANIC TIMED RELEASE DEVICES

5 AAC 39.145. ESCAPE MECHANISM FOR SHELLFISH AND BOTTOMFISH POTS. Gear must include either of the following escape mechanisms installed in the described manner:

1) A sidewall, which may include the tunnel, of all shell£ ish and bottomfish pots must contain an opening .equal to or exceeding 18 inches in length, except in shrimp pots the opening must be a minimum of six.inches in length. The opening must be laced, sewn, or secured together by a single length of untreated, 100 percent cotton twine no larger than 30 thread. The cotton twine may be knotted at each end only. The opening must be within six inches of the bottom of the pot and must be parallel with it. The cotton twine may not be tied or looped around the web bars. Dungeness crab pots may have the pot lid tie-down straps secured to the pot at one end by a single loop of untreated, 100 percent cotton twine no larger than 60 thread, as a substitute for the above requirements; the pot lid must be secured so that when the twjne degrades, the lid will no longer be securely closed.

2) A sidewall, which may include the tunnel, of all shellfish and bottomfish pots must contain an opening equal to or exceeding 18 inches in length, except in shrimp pots the opening must be a minimum of six inches in length. The opening must be laced, sewn, or secured together by a single length of treated or untreated twine no larger than 36 thread. A galvanic timed release (GTR) device designed to completely corrode in no more than 30 days in salt water must be integral to the length of twine so that when the GTR completely degrades the twine will no longer be securely attached to the web of the pot. The twine may be knotted at each end and at the attachment points to the GTR only. The opening must be within six inches of the bottom of the pot and must be parallel with it. The twine may not be tied or looped around the web bars. As a substitute for the above requirements, Dungeness crab pots may have the pot lid tie-down straps secured to the pot at one end by a single length of treated or untreated twine no larger than 36 thread. A galvanic timed release (GTR) device designed to completely corrode in no more than 30 days in salt water must be integral to the length of twine. The pot lid must be secured so that when the GTR completely degrades, the lid will no longer be secureky closed.

APPENDIX 4. DRAFT REGULATION FOR POT ESCAPE MECHANISMS: GALVANIC TIMED RELEASE DEVICES ONLY AFTER PHASE-IN PERIOD

5 AAC 39.145. ESCAPE MECHANISM FOR SHELLFISH AND BOTTOMFISH POTS. Until July 1, 1994, pot gear may include either of the following two (1 or 2, below) escape mechanisms installed in the described manner. Starting July 1, 1994, pot gear shall include escape mechanism (2 ) , below:

1) A sidewall, which may include the tunnel, of all shellfish and bottomfish pots must contain 'an opening equal. to or. exceeding 18 inches in length, except in shrimp pots the opening must be a minimum-of six inches in length. . The opening must be laced, sewn, or secured together-by a single length of untreated, 100 percent cotton twine no larger than 30 thread. The cotton twine may be knotted at each end only. The opening must be within six inches of the bottom of the pot and .must be parallel with it. . The cotton twine may not be tied or looped around the web bars. Dungeness crab pots may have the pot lid tie-down straps secured to the pot at one end by a single loop of untreated, 100 percent cotton twine no larger than 60 thread, as a substitute for the above requirements; the pot lid must be secured so that when the twine degrades, the lid will no longer be securely closed.

2) A sidewall, which may include the tunnel, of all shellfish and bottomfish pots must contain an opening equal to or exceeding 18 inches in length, except in shrimp pots the opening must be a minimum of six inches in length. The opening must be laced, sewn, or secured together by a single length of treated or untreated twine no larger than 36 thread. A galvanic timed release (GTR) device designed to completely corrode in no more than 30 days in salt water must be integral to the length of twine so that when the GTR completely degrades the twine will no longer be securely attached to the web of the pot. The twine may be knotted at each end and at the attachment points to the GTR only. The opening must be within six inches of the bottom of the pot and must be parallel with it. The twine may not be tied or looped around the web bars. As a substitute for the above requirements, Dungeness crab pots may have the pot lid tie-down straps secured to the pot at one end by a single length of treated or untreated twine no larger than 36 thread. A galvanic timed release (GTR) device designed to completely corrode in no more than.30 days in salt water must be integral to the length of twine. The pot lid must be secured so that when the GTR completely degrades, the lid will no longer be securely closed.