Long-term increases in prevalence of North Sea fishes having southern biogeographic affinities

Abstract

Observations made in the scientific and popular literature suggest that the characteristics of both marine and terrestrial ecosystems are changing rapidly due to increasing global air and sea temperatures. Here, we examine the hypothesis that fish species with more 'southern' distributions are increasing in the northern North Sea over time. In order to do this, 2 important databases on fish abundance collected by trawl on research cruises are interrogated. When combined, the databases cover both the entire North Sea and the Scottish west coast and span a period of 80 yr (1925 to 2004). The data take the form of length-frequencies for all species caught (> 300 different species), while additional information (e.g. age, sex, weight and stage of sexual maturity) is available for the commercially important component (e.g. cod). The trawl data suggest that the North Sea is experiencing waves of immigration by exotic, southern species (e.g. red mullet, anchovy and pilchard). The purpose of this paper is to describe and document these changes.KEY WORDS: Anchovy · Sardine · Horse mackerel · Mackerel · Long-term · North Sea · Climate Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 284: [269][270][271][272][273][274][275][276][277][278] 2004 doliolids are connected to unusual incursions of oceanic water caused by changes in the North Atlantic Oscillation (Edwards et al. 1999).Higher than average sea temperatures are correlated with low recruitment of cod at the latitudinal limits of its range (Planque & Frédou 1999, O'Brien et al. 2000. Reid et al. (2001) related abrupt changes in the abundance and composition of the plankton and fish community ca. 1988 to recent increases in the North Sea horse mackerel fishery. Pronounced increases in tropical fish in the Bay of Biscay area have been noted (Quero et al. 1998) by scientists in France, while Swaby & Potts (1999) made the first British record of the sailfin dory Zenopsis conchifer, noting that the species is advancing northwards along the continental shelf west of the British Isles at a rate of 60 km per decade. Other studies show similar patterns. Information on first records of southerly fish species caught in Cornish waters has been collated and published (Stebbing et al. 2002), and nearly 20 completely new species have been recorded (by 2001). The fish species noted include bigeyed tunny Thunnus obesus, sailfin dory Zenopsis conchifer, short-nosed seahorse Hippocampus hippocampus and barracuda Sphyraena sphyraena. In the Irish Sea, the occurrence of the warm-water species, anchovy Engraulis encrasicolus, has increased between 1990 and 1998 according to trawl data from research surveys (Armstrong et al. 1999). British commercial fishermen have also noted change. The spider-crab Maia squinado fishery, for example, is advancing steadily further northwards (Anonymous 2003).In 1996, a paper was published describing the longterm variation in the abundance of southern species in the southern North Sea (Corten & van...

Geographic, bathymetric and inter-annual variability in the distribution of <i>Liocarcinus depurator</i> (Brachyura: Portunidae) along the Mediterranean coast of the Iberian peninsula

“…Since demersal trawls are relatively unselective, trawl surveys can provide information not only on target species, but also on potentially key members of benthic communities. In this way, lengthy time series of trawl surveys are rare but are clearly essential for assessing the impact of natural and anthropogenic changes in benthic communities (Beare et al, 2004(Beare et al, , 2005.…”

Effect of temperature on growth, survival and respiratory rate of larval allis shadAlosa alosa

“…(2015) 416, 27 Temperature is one of the most important abiotic factors controlling the dynamics of larval assemblages of freshwater and marine fish species (Houde and Zastrow, 1993;Jakobsen et al, 2009). Many studies have linked temperature changes to distributional changes of fish stocks, mainly in marine ecosystems (Beare et al, 2004;Alheit et al, 2005;Perry et al, 2005;Pörtner and Peck, 2010) but also in freshwater ecosystems (Hari et al, 2006;Lassalle et al, 2008;Almodovar et al, 2012). However, only few studies have demonstrated temperature sensitivity of individual species based on physiological principles (Pörtner and Peck, 2010).…”

Benthos and demersal fish habitats in the German Exclusive Economic Zone (EEZ) of the North Sea

“…Distribution shifts in a sense of natural range expansion of, for example, southern species into the German EEZ were also found in the last decades. Recently, the angular crab G. rhomboides extended its distribution from the eastern Atlantic to the southern North Sea (Neumann et al 2010) and also southern fish species such as the tub gurnard Trigla lucerna, the red mullet Mullus surmuletus and the pilchard Sardina pilchardus were now regularly found in the German Bight (Ehrich and Stransky 2001;Beare et al 2004;Ehrich et al 2007). In contrast, Kröncke et al (2011) found no indications for range expansions of non-native benthic infauna species by a comparison of infauna communities between 1986 and 2000 on a North Sea wide scale.…”