LE3 .A278 2019

2019

Avery, Trevor
Quinn, Danielle

Acadia University

Bachelor of Science

Honours

Biology

Biology

Two species of skates residing in the Minas Basin and Bay of Fundy, Little Skate, Leucoraja erinacea, and Winter Skate, Leucoraja ocellata, share many morphological similarities, making them difficult to distinguish. This crypticism can cause fisheries bycatch records to be unreliable. As a result, the relative populations could be affected differentially if the species are managed or conserved as a complex. Many identification guides state Winter Skate grow larger and have eyespots whereas Little Skate are smaller and without eyespots. The study objective was to investigate differences between species commonly used to distinguish them, but which past research has suggested is not reliable. Over 11,000 skates were caught in Avon Estuary, Scots Bay, or Bay of Fundy/Scotian Shelf, Nova Scotia, and 1349 were identified to species using genetics. A subset was measured for total length, weighed, and eyespots identified (presence/absence) and/or counted. The relationship of body size, eyespots, and capture location was modeled. We found the presence of eyespots in both species to be variable and no significant relationship existed between skate size and presence of eyespots. However, regional differences were shown, but only when pooling species (thus increasing sample size), suggesting eyespots may be environmentally driven. There was potential unintentional bias in skates selected for species identification which may preclude regional results.

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https://scholar.acadiau.ca/islandora/object/theses:3303