Factors affecting the catch rate of American lobster in the eastern Gulf of St. Lawrence

1. Factors affecting the catch rate of American lobster in the eastern Gulf of St. Lawrence Daniel Gillis 12th Annual Brace Research Day April 5th 2013 "The worst day of fishing is still better than the best day at work." -Unknown

2. Lobster Fishing in Atlantic Canada Major contributor to many coastal economies for almost 200 years Lobster exports for 2012 NS – 26,000 t ($374 Million) NB – 22,000 t ($475 Million) PEI – 6,000 t ($37 Million) http://www.dfo-mpo.gc.ca/media/back-fiche/2013/hq-ac03a-eng.htm

3. Lobster trap on rock/seaweed patch

4. Me fishing in 2005

5. My father and brother in 2007

6. My father, youngest brother, and myself having lunch in 2011

7. Juvenile (left) and exceptionally large female lobster (right)

8. Large female lobster close to 18 inches long

9. A deformed lobster caught in 2007

10. Influence of Environmental Factors Fishermen have long noticed that: As water warms, catch rates increase… Westerly winds increase catch rates… Easterly winds decrease catch rates…

11. Scientists have shown that… ΔCatch = k · Δtemp (As temperature inc. or dec., catch rates follow) Drinkwater et al. 2006. Fish. Oceanogr. 15:150-165

12. Scientists have shown that… Wind influences water temperature through up/downwellings of cold/warm water Caused by Ekman currents Drinkwater et al. 2006. Fish. Oceanogr. 15:150-165

13. Ekman currents Net movement of water perpendicular to wind direction http://booksite.academicpress.com/DPO/chapter07.html

14. My B.Sc. Thesis Research NSERC Undergraduate Student Research Award May – August, 2007 Study Objective: Investigate environmental and fishing strategy variables that may affect the catch rate of lobster

15. Study Design Catch rates measured on 41 different days: Total Weight Market Weight Canner Weight Number per Trap (Sampled from 6 locations) Juveniles Temperature measured daily at 9 and 18 m depth Analysis using multiple linear regression and repeated measures ANOVA

16. Image from Google Maps

17. Image from Google Maps

18. Results Significant linear relationships (p < 0.05) with Catch Rates vs. Temp. and Time Moderately strong (R2 adj. = 0.481 to 0.680) Bait use not significant

19. Catch Rate vs. Temperature

20. Total Weight per Trap Haul

21. Weight of Markets per Trap Haul

22. Weight of Canners per Trap Haul

23. Number per Trap Haul

24. Juveniles per Trap Haul

25. Habitat Locations Analyzed Separately Time was still significant at 5 of 6 locations Temperature only significant at 2 of 6 locations Repeated Measures ANOVA revealed a significant day × location interaction

26. Day × Location Interaction

27. Conclusions Day-to-day variability in catch rates linked to temperature Accumulated fishing time has an increasing negative effect on catch rates

28. Conclusions At a spatial scale smaller than the entire habitat, effect of temperature not as strong Interaction between day × location suggests non-random (patchy) distribution of lobsters

29. Thank you for your attention Questions? Setting day last year, May 1st 2012

30. Thank you for your attention Questions? Ominous weather, June 2007

31. Thank you for your attention Questions? A visitor, May 2007

32. Thank you for your attention Questions? A beautiful day on the water, May 2007

33. Thank you for your attention Questions? A rare blue lobster, June 2007

34. Thank you for your attention Questions? Just another day on the water, June 2007

35. Thank you for your attention Questions? Breakwater at Inverness Harbour, June 2007