Predation on early life stages is decisive for year-class strength in the Barents Sea capelin (Mallotus villosus) stock

Abstract

Year-class strength of Barents Sea capelin has been monitored closely since the early 1970s and during this 45 years period three short periods of almost total recruitment failure leading to three stock collapses have been observed. These events triggered much attention since there was a large commercial fishery for capelin, but also because of observed ecosystem effects attributed to the first of these collapse events. This attention motivated research to clarify mechanisms behind the recruitment failures, and many papers have been published regarding the causes of these events. Here, we review this literature and try to put the various investigations into context. Most of the research conducted gives evidence in favour of a hypothesis that was formulated after the first recruitment failure event in the mid-1980s that predation on capelin larvae was the main cause of recruitment failure. Most studies also support the hypothesis that young herring (Clupea harengus) was the main predator on capelin larvae, but other predators like young-of-the-year cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) probably also played a role. Investigations of the effect of predators such as haddock, red king crab (Paralithodes camtschaticus), diving birds, and capelin on the demersal capelin eggs have also been reviewed. Usually, these predators are found to consume capelin eggs, but most likely not to an extent that would affect the recruitment to a noticeable degree. It is concluded that the predation on capelin larvae is the main reason for the observed recruitment failures, although predation from the predators reviewed here can hardly be the only reason for almost total recruitment failures observed in some periods.

Life history genomic regions explain differences in Atlantic salmon marine diet specialization

“…Figures 6 & 7). Capelin is a key component in the Barents Sea ecosystem with critical bottom-up influence on the dynamics of many marine organisms, including cod, birds, and sea mammals (Gjøsæter et al 2016). Capelin abundances have fluctuated considerably over recent decades, with some critical collapses mainly induced by occasional juvenile herring fluxes to the Barents system (Gjøsæter et al 2016).…”

“…Capelin is a key component in the Barents Sea ecosystem with critical bottom-up influence on the dynamics of many marine organisms, including cod, birds, and sea mammals (Gjøsæter et al 2016). Capelin abundances have fluctuated considerably over recent decades, with some critical collapses mainly induced by occasional juvenile herring fluxes to the Barents system (Gjøsæter et al 2016). Capelin schools occupy feeding grounds in the central and northern Barents Sea, and they migrate to the coastal regions for spawning (Gjøsæter et al 2016), the time at which salmon post-smolts and returning adults utilize them as a food resource (Rikardsen and Dempson 2010, this study).…”

“…Capelin abundances have fluctuated considerably over recent decades, with some critical collapses mainly induced by occasional juvenile herring fluxes to the Barents system (Gjøsæter et al 2016). Capelin schools occupy feeding grounds in the central and northern Barents Sea, and they migrate to the coastal regions for spawning (Gjøsæter et al 2016), the time at which salmon post-smolts and returning adults utilize them as a food resource (Rikardsen and Dempson 2010, this study). Individuals with the vgll3*L allele, which is associated with a later sea-age at maturity (Barson et al 2015), were marginally less likely to feed on capelin, particularly in older age groups (2SW and 3SW).…”

Effects of changes in alternative prey densities on predation of drifting lake sturgeon larvae (Acipenser fulvescens)

“…In some systems, predation is the driving factor affecting larval recruitment, as exemplified by alewife (Alosa pseudoharengus) predation on mortality rates of larval yellow perch (Perca flavescens; Mason and Brandt 1996), and the effect predator density has on the recruitment of larval capelin (Mallotus villosus; Gjøsaeter et al 2016). It can be difficult to investigate predation effects in natural systems as fish larvae often require specialized techniques to be detected in predator diet analysis (e.g.…”

Molecular diet analysis reveals predator–prey community dynamics and environmental factors affecting predation of larval lake sturgeon Acipenser fulvescens in a natural system

“…The early life stages of many fishes are subject to high mortality rates and impose a bottleneck to recruitment for many species (Hjort, ; Houde, ). Egg and larval stages of many fishes are particularly vulnerable to predation (Gjøsæter et al ., ; Mason & Brandt, ; Pine et al ., ). Predation on the early life stages of fishes can influence recruitment of otherwise highly abundant populations (Silbernagel & Sorenson, ) and can inhibit recovery in populations already experiencing low natural recruitment (Dudley & Matter, ; Köster & Möllmann, ).…”