Winter Flounder Stock Enhancement: Examining the Onset of Wild Weaning in

Pellet-Reared Fish

Stacy Farina, Michelle L. Walsh, and W. H. HowellThe Department of Biological Sciences

University of New Hampshire, Durham, NH 03801

1

A Little About Myself

2

Science Consortium for Ocean Replenishment (SCORE)

• Enhancement of natural marine populations– Invertebrates and Fish

• Sponsored by NOAA NMFS & NOAA Aquaculture

• UNH: Winter Flounder

http://www.stockenhancement.org 3

Why Winter Flounder?

4http://www.nefsc.noaa.gov/sos/spsyn/fldrs/winter/

Commercial Importance

5http://weblogs.baltimoresun.com/entertainment/dining/reviews/blog/WholeFlounder.jpg

6

Recreational Importance

http://mordantorange.com/images/comics/animals/shinybait.gif

Why Winter Flounder?

7http://www.nefsc.noaa.gov/sos/spsyn/fldrs/winter/

*

* Gulf of Maine

Possible Solution:Stock Enhancement

8

• Winter flounder vulnerable in early life stages

• Spawn and raise fish in captivity

• Release to enhance natural stocks

• Problem: Weaning onto Wild Diets

Weaning?

Transitioning to a wild diet once released

9

Winter Flounder Diet

• Captivity– Formulated Pellets (most common)• inexpensive and easy

• Wild– Live diet (worms, zooplankton, etc)

10

Why is weaning important?

Transitioning to a live diet can be stressful!

11http://www.nmfs.noaa.gov/fishwatch/species/winter_flounder.htm

YIKES!

12

Our Project

Examine the transition of pellet-reared winter flounder onto a wild diet once released

13

Methods• Spring 2007• Juvenile winter flounder reared in the Laboratory

• Summer 2007• Released in cages (10 fish per cage) in a cove– UNH’s Coastal Marine Laboratory

• Cages were retrieved every 3 hours after release up to 51 hours

14

15

Nate Rennels

Mick Walsh and Laughlin Siceloff

16

Methods• Fall 2007 – Summer 2008• Fish dissected • Stomach contents were examined and quantified

17

Results and Discussion

Get ready for some graphs!http://www.nmfs.noaa.gov/fishwatch/species/winter_flounder.htm

18

Onset of Feeding

% Fish With Food in Stomach per Retrieval

After 18 hours, the number of fish feeding was significantly higher than at 12 hours after release. (p < 0.05)

19

Diet Composition

Most commonly selected prey: Polychaetes (48.2%) and Copepods (31.2%)

20

Polychaete Worms

Bivalves

Copepods

Nematodes

21

Diet Composition

First 12 hours• Inorganics (rocks)

22Values Based on IRI Calculations

Diet of Wild Fish (Katie Robertson)

23

Extent of Feeding

24

What Can We Conclude?• After 18 hours, most fish had food in their stomachs.

• Inorganics were common within the first 12 hours, but minimal after.

• Diet was composed of mainly polychaete worms and crustaceans (copepods and amphipods), and was similar to that of wild fish.

• Gut fullness increased with time.

25

Ongoing Work

• Long-term studies of feeding, growth, and survival after release

• Examine impact of live laboratory diets on onset and quality of weaning

• Assess feeding behavior of winter flounder raised on formulated pellets

26

Ongoing Work

27

Acknowledgments

We gratefully acknowledge Elizabeth A. Fairchild, Nate Rennels, Travis Ford and Laughlin Siceloff for their assistance with experimental design and field work, and Kristin Garabedian and Katie Robertson for help with dissections and data entry. We thank the laboratories of Jim Haney and Larry Harris for use of their equipment. This project was funded by the University of New Hampshire’s Hamel Center for Undergraduate Research, The Graduate School and the Science Consortium for Ocean Replenishment (SCORE), a division of the National Oceanic and Atmospheric Administration (NOAA).