Spatiotemporal overlap of spiny dogfish (Squalus acanthias) and commercial fisheries in the northeast U.S. shelf large marine ecosystem

Abstract

Abstract-Commercial fishermen have argued that localized concentrations of spiny dogfish (Squalus acanthias) in the northeast U.S. shelf large marine ecosystem (NES LME) have impeded their fishing operations when monitoring surveys estimated lower relative abundances. Fishery-dependent and -independent data were analyzed simultaneously to examine whether increased spatial overlap between spiny dogfish and commercial fisheries may explain high catches of this species on fishing grounds. Spatial overlap was quantified between spiny dogfish distribution and commercial fisheries from 1989 to 2009 during autumn and spring in the NES LME. Combined, the sink gillnet (SGN) and otter trawl (OT) fisheries accounted for the majority of spiny dogfish catch (autumn: 85%; spring: 92%), either retained (SGN) or discarded (OT). Centers of spiny dogfish abundance illustrated spatial differences in local density within the NES LME and revealed seasonal differences in spiny dogfish density. Recent increases in spatial overlap indicate that a growing portion of the spiny dogfish stock was available to each fishery over the time series. Availability, estimated as the percentage of spiny dogfish present on fishing grounds, also increased and was generally higher during autumn than spring. Abundance of mature (total length ≥80 cm) female spiny dogfish was significantly related to availability, but trends were variable between fisheries and seasons. Although recent increases in abundance indicate recovery, research regarding the mechanisms behind these changes may help explain why abundance in the NES LME appears highly variable.

A real‐time PCR assay to detect predation by spiny dogfish on Atlantic cod in the western North Atlantic Ocean

“…Sagarese et al. (2015) note increasing overlap, as dogfish have recovered, between the distributions of dogfish and the operations of bottom trawl and gillnet fisheries. Here, we leverage this to our advantage, because it should increase the likelihood for observing cod DNA in dogfish stomachs, aiding the development of this approach.…”

“…Spiny dogfish ( Squalus acanthius Linnaeus), after being declared overfished on the northeast U.S. continental shelf in 1998, recovered in about a decade to a higher but variable abundance (Sagarese et al., 2015). Historic diet data suggest that spiny dogfish's role as a piscivorous predator of several groundfish has not been significant (Link, Garrison, & Almeida, 2002), but a recent, simulated food web model suggests that spiny dogfish's role as a competitor and predator has changed as its population has shifted from a depleted to a rebuilt state (Morgan & Sulikowski, 2015).…”

Improving the interpretation of fishing effort and pressures in mixed fisheries using spatial overlap metrics

“…In their study, Sagarese et al (2015) also quantified the overlap between fish distribution from survey data and fishing effort, in order to quantify the availability of spiny dogfish to sink gillnetters and otter trawlers. However, their approach was designed in a binary fashion (i.e.…”