The apparent disappearance of Loligo forbesi from the south of its range in the 1990s: Trends in Loligo spp. abundance in the northeast Atlantic and possible environmental influences
|Author(s)||Chen C1, Pierce G1, Wang J1, Robin J2, Poulard Jean-Charles3, Pereira J4, Zuur A5, Boyle P1, Bailey N6, Beare D6, Jereb P7, Ragonese S8, Mannini A9, Orsi-Relini L9|
|Affiliation(s)||1 : Univ Aberdeen, Sch Biol Sci, Aberdeen AB24 2TZ, Scotland.
2 : Univ Caen, IBFA, Lab Biol & Biotechnol Marines, F-14032 Caen, France.
3 : IFREMER, Dept Ecol & Modeles Halieut, EMH, F-44311 Nantes, France.
4 : IPIMAR, P-1449006 Lisbon, Portugal.
5 : Highland Stat Ltd, Newburgh AB41 6FN, Aberdeen, Scotland.
6 : Marine Lab, Fisheries Res Serv, Aberdeen AB11 9DB, Scotland.
7 : ICRAM, I-00166 Rome, Italy.
8 : Inst Coastal Marine Environm, Sect Mazara Vallo, I-91026 Mazara Del Vallo Trapani, Italy.
9 : Univ Genoa, Lab Biol Marine & Ecol Anim, Dip Te Ris, DIPTERIS, I-1626 Genoa, Italy.
|Source||Fisheries Research (0165-7836) (Elsevier), 2006-04 , Vol. 78 , N. 1 , P. 44-54|
|WOS© Times Cited||31|
|Keyword(s)||North Atlantic Oscillation NAO, Dynamic factor analysis, Common trends, Abundance, Squid fishery, Loligo|
|Abstract||Since the early 1990s, Loligoforbesi has apparently disappeared from much of the southern part of its former range, with catches off the Iberian Peninsula, for example, declining dramatically during the 1990s. The present paper assembles data from fishery and research cruise databases to examine the evidence for a shift in distribution, examine the relationship between abundance of this species and that of the partially sympatric Loligo vulgaris, and identify possible environmental correlates. Time-series of abundance of L. forbesi and L. vulgaris were assembled using fishery and survey data from Scotland, France, and Portugal. Based on availability of data and timing of the main fishery, data for autumn (October-December) were selected. Nine squid series and two explanatory variables (October sea surface temperature and the winter NAO index) were analysed using dynamic factor analysis (DFA). The optimal DFA model contained two common trends and both of the explanatory variables. The first common trend shows an increase from 1987 to 1999, and a slight decrease after 2000 onwards, and is positively related to L. forbesi abundance in the north of its range (Scotland), while negatively related to squid abundance (both species) in the south of their ranges (France and Portugal). The second trend identifies an increase from 1990 to 1995, followed by a decrease until 2002, and is positively related to the squid (L. forbesi and L. vulgaris) abundance series from French surveys and fisheries. The SST series was significantly related to three squid abundance series: positively with abundance of small L. forbesi in French surveys and negatively with the abundance of small L. forbesi from Scottish surveys and abundance of L. vulgaris in Portuguese surveys. The winter NAO series was significantly related to the abundance of small L. forbesi from Scottish surveys. The increase in SST after 1993 and subsequent high level may thus be associated with the decrease of Loligo abundance in the south area (France and Portugal) and the increase in Loligo abundance in the north area (Scotland).|