In the Gulf of Maine–Bay of Fundy region of the Western Atlantic, there are three distinct spawning groups of herring: Nova Scotia, coastal Gulf of Maine, and Georges Bank/Nantucket Shoals (Reid et al., 1999). The Atlantic herring resource along the East Coast of the United States was originally divided into separate Gulf of Maine and Georges Bank stocks (Figure 22.1), but herring from the Gulf of Maine and Georges Bank components are now combined into a single coastal stock complex, because fisheries and surveys include fish originating from all spawning areas off New England (NEFSC, 2012). Copyright © 2020 Elsevier B.V. or its licensors or contributors. The global catches of herring have amounted to several million tonnes. The analysis of pectoral ray counts has historically been considered one of the more effective ways to discriminate spawning groups. This was confirmed by estimating the average size of individual herring recorded in the summer RV survey. Funding was provided by the Canadian Department of Fisheries and Oceans Strategic Program for Ecosystem-Based Research and Advice (SPERA Grant #: 21714-805-120) and the Natural Sciences and Engineering Research Council of Canada (NSERC Grant #: RGPGP-2015-00076) Team Discovery Grant to K.T.F. Three indicators were marginally non-significant (p = 0.1–0.05; Figure 2a, grey points). For example, interpreting the declining trends in condition (mass, length, condition, weight-at-age) as unhealthy depends in part on the magnitude of the population biomass. (2012) demonstrated a 3-D machine vision system developed for the weight estimation of pelagic fish, based on the finding reported in Mathiassen et al. Conversely, an increase in TAC may result in increased commercial benefits at the expense of reduced ecosystem benefits. B. S.
Health is a useful metaphor for understanding population status as it incorporates a broader suite of factors than most traditional stock assessments and has the potential to provide a deeper, more robust understanding than any single indicator. R. L.
Additionally, Atlantic herring exhibit variability in the timing of spawning, with spring and autumn spawners often occupying the same spawning locations. Our analysis did not seek to resolve the debate over the true level of herring SSB or which methodology is preferable (VPA, acoustic, or observational), but instead to integrate all available information to understand how the overall status, or health, of the population, has changed over time. These concerns originate from assessments that had reported a prolonged period (1978–2001) when landings commonly failed to meet allowable quotas (Figure 1a), and large reductions in spawning stock biomass (SSB) and recruitment occurred. McQuinn (1997) proposed an alternate explanation for herring population structure that was framed within the metapopulation concept and can account for the loss and recolonization of spawning areas. a reduction in TAC) may imply reduced benefits of commercial harvest; and, as an offset, we may realize added benefits for the ecosystem from the ER. Natal homing ensures that adult fish always spawn on the spawning grounds where they themselves hatched (Iles and Sinclair, 1982). DFO Can. K. R.
Spatial dynamics: Geographic range, decorrelation, fine-scale decorrelation, spatial variance, spatial coefficient of variation. North Sea herring are managed as a single stock, although the presence of multiple spawning components is acknowledged and the importance of preserving this diversity is recognized. Hence the annual mortality each year of the eggs, larvae and juveniles is high; indeed, it is approximately the inverse of the annual fecundity. For (b) and (c), grey lines denote the 200-m isobaths. The North Sea herring migrate in a clockwise circuit in the North Sea (Figure 1). The remaining cluster (C4) was moderately well-defined (n = 6; r = 0.2), and exhibited a declining but highly variable trend. They live and swim in large shoals, each of which may be many kilometers across. The migration circuit of the spring spawning Norwegian herring; the spawning ground lies off the Norwegian coast, the nursery ground spreads north into the Barents Sea and the feeding ground lies between Iceland and Spitzbergen. A. D.
For seven series, declines were underway from at least the start of the series; for these, the first year was taken as the changepoint. and W.C. Leggett. The steps to assess herring population health were (i) data acquisition, (ii) defining the spatiotemporal domains, (iii) extracting/estimating the indices related to health, (iv) standardization and (v) statistical analysis and integration. Adopting this approach, we quantified herring dynamics over five decades, overcoming the current reliance on the short-term and uncertain estimates of abundance. For marine fish populations, this stringent requirement is rarely met. Two opposing concepts of Atlantic herring, Clupea harengus L., population structure are critically reviewed with the objective of unifying these divergent views under the metapopulation concept. In 2004 larval abundance dropped again by ∼90% on Georges Bank (Richardson et al., 2010). An extension of this hypothesis is that the spawning success of herring within a region depends on swamping the predator field. Brophy and Danilowicz (2002) used larval otolith microstructure measurements in juvenile herring to confirm that the Irish Sea is an important nursery area for winter-spawned Celtic Sea herring and showed that dispersal into the Irish Sea most likely occurs early in the larval phase. (For color version of this figure, the reader is referred to the online version of this book. Atlantic herring (C. harengus L.) populations are characterized by their complex structure, with populations and subpopulations spawning at specific locations and during discrete seasons (Blaxter and Holiday, 1963; Iles and Sinclair, 1982; Geffen, 2009). Lines delineate the four identified clusters; shaded points depict the level of statistical significance of the time-dependent variation in the individual indices estimated from time-series models. (a) Landings of herring in NAFO Division 4WX separated by major fisheries. The intense demand for herring coupled with their central role within many marine food webs has raised concerns about their overexploitation and conservation status locally and globally (Power et al., 2006; FAO, 2014). (a) Cluster analysis of herring time-series. Field studies (Marshall et al., 2006; Hixon et al., 2014) and meta-analyses (Barneche et al., 2018) report that fish fecundity increases disproportionately with body weight and that larger females produce larger offspring with higher survivorship (Hixon et al., 2014; Lim et al., 2014). These results are contrary to previous reports of year-class twinning (covariance in the year-class strength of the two components, which occurs due to a large proportion of herring spawned in one season recruiting to another seasonal spawning group) as evidenced by gonad analysis and hatching season determination by visual inspection of otolith nucleus opacity in Newfoundland herring populations (Mcquinn, 1997b).