First‐year survival of North East Atlantic mackerel (Scomber scombrus) from 1998 to 2012 appears to be driven by availability of Calanus, a preferred copepod prey

Abstract

Mackerel (Scomber scombrus) is one of the ecologically and economically most important fish species in the Atlantic. Its recruitment has, for unknown reasons, been exceptional from 1998 to 2012. The majority (75%) of the survivors in the first winter were found north of an oceanographic division at approximately 52°N, despite the fact that mackerel spawns over a wide range of latitudes. Multivariate time series modelling of survivor abundance in the north revealed a significant correlation with the abundance of copepodites (stage I–IV) of Calanus sp. in the spawning season (April to June). The copepodites were a mix of C. helgolandicus (dominating) and C. finmarchicus. The growth of mackerel larvae is known to be positively related to the availability of nauplii and copopodites of preferred prey species, namely, large calanoid copepod species such as Calanus. The statistical relationship between mackerel survivors and abundance of Calanus, therefore, most likely, reflected a causal relationship: high availability of Calanus probably reduced starvation, stage‐specific predation and cannibalism (owing to prey switching). The effects of other abundant, but less preferred zooplankton taxa, (Acartia sp., Branchiopoda spp. and Echinodermata spp. larvae), as well as stock size, temperature and wind‐induced turbulence were not found to be significant. However, stock size was retained in the final model because of a significant interaction with Calanus in oceanic areas west of the North European continental shelf. This was suggested to be a consequence of a density driven expansion of the spawning area that increased the overlap between early life stages of mackerel and food (Calanus) in new areas.

Exploring the Influence of Food and Temperature on North Sea Sandeels Using a New Dynamic Energy Budget Model

“…The sandeel stock may be suppressed by other pelagic fish. For example, the abundance of mackerel, which prey on sandeels and compete for food (Jones, 1983), has increased substantially in the North Sea since 2000 (Engelhard et al, 2008;Jansen, 2016).…”

Tracking shifts in Atlantic mackerel (Scomber scombrus) larval habitat suitability on the Northeast U.S. Continental Shelf

“…Poor spatial‐temporal match between larvae during the transition from yolk‐sac to exogenous‐feeding and their preferred prey can influence growth and mortality through increased starvation and susceptibility to predation (Takasuka, Aoki, & Mitani, ). In the northern contingent, Atlantic mackerel recruitment has been found to vary annually based on prey availability during the species’ exogenous‐feeding larval stage (Castonguay, Plourde, Robert, Runge, & Fortier, ; Plourde et al., ; Jansen, ). Changes in dominant zooplankton taxa could also influence future mackerel recruitment of the southern contingent.…”

Atlantic bluefin tuna (Thunnus thynnus) in Greenland — mixed-stock origin, diet, hydrographic conditions, and repeated catches in this new fringe area

“…The recent pattern of annual seasonal occurrence is evident despite the unintentional nature of the data source and collection method: that is, the presence is documented only from monitored bycatches in commercial fisheries and does not originate from targeted bluefin tuna surveys or fisheries. On this basis, we cannot estimate the total abundance in the area, extent of the season (the season of the mackerel fishery starts in mid June and ends in mid September (Jansen et al, 2016)), or the total spatial distribution of the Atlantic bluefin tunas in this region because the fishing vessels involved were targeting other species in a limited time and area. The capture of bluefin tunas in mackerel fishery hauls is consistent with the known diets of bluefin tunas in northern feeding areas: mackerel are an important prey species in many of these areas (Tiews, 1978;Chase, 2002;Pleizier et al, 2012), and it is likely that Atlantic bluefin tuna in east Greenland waters were captured while foraging directly on mackerel schools (as also supported by our limited stomach sampling data), or were within close proximity to such schools.…”

“…This species has spread westward into Greenland waters simultaneously with the tuna and could have provided a foraging trail and stimulus for bluefin tuna to enter east Greenland waters. The range expansion of mackerel is believed to be due to a complex interaction between rising temperatures, mackerel population dynamics, and the abundances of zooplankton (Trenkel et al, 2014;Jansen, 2016;Jansen et al, 2016;Olafsdottir et al, 2019). This may therefore be regarded as a cascading spatial bottom-up effect from physics and plankton, via mackerel to tuna.…”