Search

We investigated the effect of environmental conditions on Atlantic mackerel spawning habitat in the southern Gulf of St. Lawrence (sGSL). Based on generalized additive models, we (i) modelled the optimal spawning habitat of mackerel in the sGSL using daily egg production (DEP) in June, (ii) predicted known and new potential present spawning habitats in the GSL and the north‐west Atlantic, and (iii) assessed how they respond to future climate change. Our findings showed that both mackerel presence–absence and given‐presence DEP were associated with sea surface temperature (10–16.5°C), salinity above 31 and depth < 120 m. Adding zooplankton showed a marked effect on the DEP given‐presence compared to the presence–absence. Predictions of spawning habitats under present (1999–2012) and future scenario (2066–2085) conditions were estimated from the presence–absence model without zooplankton, using physical conditions of the BNAM. Under present conditions, our model predicted well the main spawning habitat in the sGSL and other known secondary spawning habitats in the northern GSL (nGSL), the western and southern Newfoundland, and the north‐west Atlantic coast. Under future conditions, our study suggests that spawning habitats in the sGSL and the nGSL would expand. Our results, therefore, suggest that mackerel could benefit from a warmer GSL, minimizing the potential for a northward migration of the stock due to decreasing suitability of the sGSL as its main spawning ground, and a new but spatially limited potential habitat in Newfoundland coasts. These results can be used to inform stock management and develop adaptive management plans in the context of climate change. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Globally, management decisions for recently established invertebrate fisheries are based on limited information. The negative consequences are being realized as now at least one-third of invertebrate fisheries are over-exploited, collapsed or closed. Management of a fishery should be based on abundance and productivity data. This information is often unavailable but in some jurisdictions, spatial distributions are known. A methodology for designating a network of reserves for sedentary invertebrates, using sea cucumber ( Cucumaria frondosa) on the Scotian Shelf, Canada is proposed, as a case study., It is assumed that there is a positive relationship between spawner density and per capita population growth rate in sedentary broadcast spawners and that fertilization success declines rapidly at low densities. Protection of high-density habitat would safeguard critical spawner density, especially when the critical density is unknown. Using spatial distribution, a method to identify size and location of reserves designed to protect high-density habitat was developed., First, geographically distinct regional-scale clusters are identified. Within clusters, the characteristic patch scale was determined through spatial autocorrelation analysis. The size of reserves can be set as 50% of each high-density patch based on an appropriate risk-averse approach., The allocation of reserve size and location is not dependent on results of a numerical circulation model. However, the analysis was refined by using one to predict larval drift patterns, and connectivity among patches. Reserve boxes were then designated to safeguard from 30 to 65% of each high-density patch., Marine reserves do not work if inappropriately sited. In the absence of any other information, it is argued that siting reserves on high-density areas is an essential and appropriate approach to data-poor invertebrate fisheries management. A high percentage of each high-density patch could serve as risk-averse 'spatial management' reference points, and could be modified once replenishment rates are known., Copyright © Her Majesty the Queen in Right of Canada 2013 [ABSTRACT FROM AUTHOR]