PARENT SESSION
Oral Session # 3: Fish Ecology.
Presiding: M Ford
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 102.
Comparative foraging behaviors of slimy sculpin and deepwater sculpin.
Hondorp, Darryl*,1, 2, Brandt, Stephen2, 1 Cooperative Institute For Limnology & Ecosystems Research (CILER)-University of Michigan, Ann Arbor, MI, USA2 NOAA-Great Lakes Environmental Research Laboratory (GLERL), Ann Arbor, MI, USA
ABSTRACT- Sympatric populations of ecologically similar fish often exhibit variation in food and habitat use that is related to interspecific differences in morphology, feeding behavior and the elusiveness of potential prey. In this paper, we examined how these factors interact to influence the prey and habitat selection patterns of slimy sculpin (Cottus cognatus) and deepwater sculpin (Myoxocephalus thompsoni) in the Laurentian Great Lakes. Conclusions were based on results from a series of feeding experiments where slimy and deepwater sculpin were videotaped while foraging on the benthic amphipod Diporeia hoyi and the freshwater shrimp Mysis relicta. Both Diporeia and Mysis are key constituents of the diet of these fish. Preliminary results indicate that both sculpin have significantly greater capture success rates with Diporeia than with the more elusive Mysis. Mysis have a keen ability to detect and evade foraging sculpins. When attacked, strong thrusts of the telson accelerate mysids rapidly away from the predator, a behavior that greatly increases the probability of escape. Diporeia lack any notable predator defenses and are therefore more easily captured. Results also indicated that deepwater sculpin capture Mysis with greater success than do slimy sculpin. This difference in feeding performance suggests interspecific variation in sculpin prey detection capabilities and strike mechanics and may help explain the consistent pattern of depth segregation exhibited by these sculpin species in the Laurentian Great Lakes.
Key words: habitat partitioning, foraging ecology, sculpin, Laurentian Great Lakes