Date of Award

Fall 2016

Project Type

Dissertation

Program or Major

Zoology

Degree Name

Doctor of Philosophy

First Advisor

Elizabeth A Fairchild

Second Advisor

William H Howell

Third Advisor

Winsor H Watson

Abstract

Channeled whelks (Busycotypus canaliculatus) are predatory marine gastropods that support lucrative commercial fisheries along the east coast of the United States, with areas around Massachusetts supplying the largest landings. In the absence of a more thorough and comprehensive understanding of channeled whelk biology, it is unclear how to sustainably manage their fisheries. Within this dissertation, various aspects of whelk ecology were investigated to determine how to protect this species, while effectively managing the local fishery.

Early life history experiments revealed channeled whelk egg strings may incubate for 8 to 9 months in MA water temperatures. Incubation period decreased with increasing water temperatures, but no live juvenile whelks hatched from the warmest constant water temperature treatment, 25C. Growth rates for whelks cultured in MA ambient water conditions were seasonal, with fastest growth occurring in warm seasons. Survival during hatching period was low (14.9 ± 2.8 %), and after 2.5 years approximately 0.5 ± 0.1 % of hatched whelks had survived.

Preliminary investigations into channeled whelk reproductive ecology indicate oviposition extends up to two weeks, and video footage showed females did not move or feed throughout the egg laying process. Sperm storage capabilities > 1 year were observed, indicating female channeled whelks can delay spawning periods, perhaps to coincide with favorable conditions. While egg strings and embryos varied in length and number, more research is needed to understand whelk size influences fecundity.

In-situ growth rates from tag and recapture experiments in Nantucket Sound suggest female whelks grow faster (8.08 2.06 mm/year) than males (6.07 2.02 mm/year). Results, additionally showed growth may differ between areas within Nantucket Sound. All growth rates declined with days at large indicating, growth slows as size increases.

Throughout a 14-month whelk tracking study, telemetry results showed whelks remained within 200 m of release site, indicating small home ranges. Whelks appeared to move toward channel opening during the spring, but it is unclear if this movement was an effect of dredging. No movement was exhibited from July to August for all tagged whelks, corresponding with declines in commercial catch.

The whelk trap video system proved to be an effective, low-cost, and transportable tool to examine whelk behaviors. Day/night video footage was possible for at least 76 (near) continuous hours, allowing preliminary examinations into trap efficiency, daily feeding behaviors, and gear interactions. Results indicate channeled whelks exhibit nocturnal feeding behaviors and that whelk traps are very efficient at capturing whelks, with only 2 small whelks escaping through the trap’s wire mesh (4 x 4 cm).

Overall, research within this dissertation provides lacking information on channeled whelk ecology. With results indicating low juvenile survival, small home ranges, and highly efficient fishing gear, whelk management practices need to be re-evaluated.

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