Observations on spiny dogfish (Squalus acanthias) captured in late spring in a North Carolina estuary

Charles Bangley,Roger Rulifson

doi:10.12688/f1000research.4890.1

Abstract

Five spiny dogfish were captured in early-mid May during gillnet and longline sampling targeting juvenile coastal sharks in inshore North Carolina waters. Dogfish captures were made within Back Sound and Core Sound, North Carolina. All dogfish were females over the size at maturity, and were caught at stations 1.77-2.74 m in depth, with temperatures 22.9-24.2 °C, 32.8-33.4 ppt salinity, and 6.9-8.0 mg/L dissolved oxygen. Stations where dogfish were captured were approximately 6.5-15.7 km from the nearest inlet and 43.4-247.1 m from the nearest seagrass bed. These observations are among the latest in the spring for spiny dogfish in the southeastern U.S. and occurred at higher temperatures than previously recorded for this species. It is unclear whether late-occurring spiny dogfish in this area represent a cryptic late-migrating or resident segment of the Northwest Atlantic population.

Highlights

The spiny dogfish (Squalus acanthias) is a small, highly migratory coastal shark common in Northwest Atlantic waters from Newfoundland to Cape Hatteras (Stehlik, 2007)
After signs of population disturbance resulting from overfishing, stringent fishery management regulations were put in place for this species, and the population was considered recovered within ten years of implementing a fishery management plan (Rago & Sosebee, 2010). Such a swift recovery was unexpected for this species due to its life history characteristics: spiny dogfish in the Northwest Atlantic are not reproductively mature until an age of 12 years, have a 2-year gestation period, and give birth to only 1–15 young (Nammack et al, 1985)
Other species captured at this site included one cownose ray (Rhinoptera bonasus, DW = 414 mm), one bullnose ray (DW = 458 mm), and four harvestfish (Peprilus alepidotus). This site was 15670.63 m from the nearest inlet and 247.08 m from the nearest mapped seagrass bed. These observations represent the highest reported temperatures and latest occurrence for spiny dogfish in their overwintering habitat off the Southeastern U.S, with the exception of those captured on June 1, 2010 by Rulifson et al, (2012)

Summary

Introduction

The spiny dogfish (Squalus acanthias) is a small, highly migratory coastal shark common in Northwest Atlantic waters from Newfoundland to Cape Hatteras (Stehlik, 2007). After signs of population disturbance resulting from overfishing, stringent fishery management regulations were put in place for this species, and the population was considered recovered within ten years of implementing a fishery management plan (Rago & Sosebee, 2010). Such a swift recovery was unexpected for this species due to its life history characteristics: spiny dogfish in the Northwest Atlantic are not reproductively mature until an age of 12 years, have a 2-year gestation period, and give birth to only 1–15 young (Nammack et al, 1985). Spiny dogfish tagged with pop-up satellite tags in the Gulf of Maine were tracked moving off the continental shelf, providing more evidence for inshore-offshore migrations (Sulikowski et al, 2010)

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Conclusion