The utility and limitations of genetic data for stock identification and management of North Pacific rockfish (Sebastes spp.)

Abstract

Rockfishes (Sebastes spp.) represent a speciose and ecologically important group of marine fishes found in both the Pacific and Atlantic oceans, with approximately 105 species found world-wide (Hyde and Vetter 2007). They also comprise the majority of species found in the Pacific groundfish fishery. Thorough species assessments in terms of harvest management have been done for only 11 species, and of the 11 species, seven have been declared overfished. Having accurate genetic information is critical to the continuing effort at stock assessments, but sampling is often difficult in marine fishes. Genetic techniques are a powerful tool in the effort to better characterize the ecology of these species. These techniques can be used to investigate multiple biological traits, including species identity, intra-and interspecific genetic variation, migration patterns, and effective population size. There are important caveats and limitations when applying specific genetic methods, especially in marine species that lack discrete spawning aggregates. Nevertheless, it is clear from a review of recent literature that genetic tools have already provided very specific insight regarding rockfish population dynamics. The results are diverse and difficult to synthesize; however, existing studies show five primary patterns to population groupings in rockfishes: no obvious pattern of structure, structure consistent with isolation by distance, structure evident but inconsistent with isolation by distance, structure that correlates to oceanographic features, and potential genetic introgression. Clearly the study of rockfish population genetics is poised for rapid expansion that will unquestionably aid management of the rockfish fisheries and general understanding of rockfish evolutionary systematics. A principle challenge at this point is to derive generalized inferences from such a diverse array of study results across the vast North Pacific range of Sebastes. This review summarizes existing genetic studies in Sebastes spp. in the North Pacific to assist in identifying knowledge gaps for this ecologically important and diverse group.

Stock boundaries for fisheries assessment and management in the Mediterranean: the Balearic Islands as a case study

“…fishing exploitation) interactions among areas. In fact, it has been shown that stocks do not have to be completely isolated from one another to show demographic independence (Brown et al 1987;Berntson and Moran 2009). …”

Evaluation of rockfish conservation area networks in the United States and Canada relative to the dispersal distance for black rockfish (Sebastes melanops)

“…Many other rockfish species share this shallow depth preference (Table , Love et al. ; Berntson and Moran ) and are unlikely to be protected by the deepwater reserves. The lack of nearshore reserves in Washington therefore violates criteria ii for nearshore rockfish species.…”

“… 2010 ). Indeed, genetic differentiation has been found between these inner waters and the outer coast in some rockfish species (Berntson and Moran 2009 ), indicating that patterns of dispersal may differ between the inner waters and outer coast.…”

Evidence of subtle genetic structure in the sympatric species Mullus barbatus and Mullus surmuletus (Linnaeus, 1758) in the Mediterranean Sea

“…However, a possible mismatch between the stock limits established by fishery managers and the biological stock boundaries can be expected. Moreover, it has been shown that stocks need not to be completely isolated to show demographic independence 15 .…”