Research Document - 2009/023
Offshore Lobster in Lobster Fishing Area 41 (4X and 5Zc)
By D.S. Pezzack, C.M. Frail, A. Reeves, and M.J. Tremblay
Abstract
The offshore lobster (Homarus americanus) fishery (Lobster Fishing Area [LFA] 41), established in 1972, fishes from the 50 nautical mile line (92km) to the upper continental slope of the Scotian Shelf and on northeast Georges Bank. While LFA 41 includes parts of the Northwest Atlantic Fisheries Organization (NAFO) divisions 4Vs, 4W, 4X and 5Z, lobster fishing is authorized only in 4X and 5Zc. The fishery is managed by input and output controls including a 82.5mm minimum size carapace length (CL), prohibition on landing berried or v-notched female lobsters, limited entry (8 licences) and a 720t Total Allowable Catch (TAC). In this assessment, indicators of abundance, fishing pressure and production are evaluated for 5 subareas (Georges Bank, Southeast Browns, Southwest Browns, Georges Basin and Crowell Basin). Based on these indicators, the current TAC of 720t (in place since 1985) does not appear to have had negative impacts on the lobster in LFA 41 (4X and 5Zc) overall, and is considered to represent an acceptable harvest strategy at this time.
Abundance indicators (trap catch rate, catch rate in Department of Fisheries and Oceans (DFO) summer bottom trawl surveys) for commercial sized lobsters in the different subareas suggest that lobster abundance has been either stable without trend or has trended higher since 1999. Fishing pressure was evaluated in terms of total trap hauls, size structure and sex ratio. Total trap hauls in 2007 (288,000) returned to levels observed in 1995 (228,000), down from the peak of 593,000 in the 1998-1999 season, presumably because of reduced fishing for Jonah crab. The size structure has remained stable except for apparent decreases in median size in Crowell Basin. A decrease in the proportion of males occurred during the first 10 years of the fishery, with the largest change on Georges Bank. The sex ratio is skewed towards more females as conservation rules protecting berried females result in lower fishing mortality on females. Exploitation rate has not been directly estimated but is inferred to be low. Landings in the larger adjacent fisheries (USA, LFA 34) increased significantly during the last 10 years, indicating additional pressure on the lobster resources in these areas. Production indicators show that there is a high proportion of females above the estimated size of 50% maturity of 97mm carapace length (CL) and above 115mm CL (most females are multiparous or multiple breeders above this size) in the LFA 41 fishery, indicating a high level of potential egg production relative to the inshore fisheries. Four assessment areas have shown no trend in this proportion over time. Indicators of lobster recruitment in LFA 41 are not currently available since the fishery is conducted primarily in deeper areas where recruitment is not expected to occur.
Potential ecosystem interactions include impacts of traps on bottom habitat, impacts of lost gear, bycatch and interactions with other species. Bycatch species that occur most frequently in the LFA 41 lobster fishery include Jonah crab, cusk, hake (red and white), cod, rock crab and redfish. Other than Jonah crab, all animals are released. High survival is assumed for invertebrates, but survival may be lower for some fish species. The effect of fishing on bottom habitat has not been evaluated but is expected to be low relative to other bottom contact gear types. This expectation is based on the small size of the gear footprint and the relatively low density of traps in this large fishing area.
Accessibility Notice
This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.
- Date modified: