Response of Scotian Shelf silver hake (Merluccius bilinearis) to environmental variability

Abstract

Commercially‐exploited fish populations are not only shaped by fishing pressure, but also by the dynamics of their environment. By quantifying the influence of environmental variability, fisheries management advice can be improved and uncertainties reduced. To this end, we developed statistical models of the response of Scotian Shelf silver hake stock metrics to variability in zooplankton community composition and phenology over the past 18 years and in the physical environment since 1985. Dominant modes of variability in these pelagic habitat indicators were characterized using principal component analysis, and the relationships of silver hake condition, abundance, and recruitment to pelagic habitat variability were assessed using generalized additive models. Condition was largely modulated by the onset and duration of the spring bloom, which controls food availability. In contrast, adult abundance was governed by composition of the zooplankton community and bottom‐water temperature, which dictates the distribution of silver hake. Finally, recruitment was affected by both thermal conditions and food availability. Our results presented here form the basis for qualitative assessment of ecosystem attributes and the influence on silver hake stock productivity.

Climate Change Vulnerability of American Lobster Fishing Communities in Atlantic Canada

“…During their planktonic stage, they inhabit near-surface waters where they complete three molts by feeding mostly on other planktonic organisms (DFO, 2009). C. finmarchicus is biomass dominant in the zooplankton assemblages in this region of the northwest Atlantic (Reed et al, 2018). Since phytoplankton are the primary source of nutrients for C. finmarchicus, their lifecycle is highly dependent on the timing and magnitude of seasonal blooms.…”

Temporal and spatial distributions of delphinid species in Massachusetts Bay (USA) using passive acoustics from ocean gliders

“…Prey switching by delphinids or shifts in prey distribution may explain inter-annual differences in spatial distributions of delphinids. Fish distributions in Stellwagen Bank National Marine Sanctuary show associations with seafloor habitat and sediment type (Auster et al 2001) and may also be related to zooplankton abundance and diversity (Reed et al 2018). Copepod density and diversity were correlated with sighting rates of common dolphins and striped dolphins Stenella coeruleoalba (Griffin 1997).…”

Variation in energy density of northwest Atlantic forage species: Ontogenetic, seasonal, annual, and spatial patterns

“…The spatial distribution of Silver Hake has shifted poleward in the past 40 years, and their increasing abundance in the GOM is correlated to the position of the Gulf Stream (Nye et al 2011). In addition to oceanographic drivers influencing the spatial distribution of Silver Hake, Reed et al (2019) found that the condition of Silver Hake on the Scotian Shelf was largely determined by zooplankton phenology and community composition and was largely unrelated to density-dependent effects. A geospatial analysis of Silver Hake in the GOM indicated that condition varied over small spatial scales and that the population conformed to the proportional density model, in which local population density is a static proportion of the fixed occupied range (Pereira et al 2014).…”