Postuma, F. A., and Gasalla, M. A. 2010. On the relationship between squid and the environment: artisanal jigging for Loligo plei at São Sebastião Island (24°S), southeastern Brazil. – ICES Journal of Marine Science, 67: 1353–1362. The squid Loligo plei concentrates in the southeastern Brazil Bight, where it has traditionally supported small-scale fisheries around São Sebastião Island (SSI). Sea surface temperature (SST), chlorophyll-a (Chl a), windspeed, wave height, rainfall, and lunar phase are related to fishing records and to the results of a survey of local fishers to investigate how they believe environmental variables might affect catches of L. plei. Daily fishery-dependent data over the years 2005–2009 were obtained from a fishing cooperative and were matched with satellite and meteorological forecast data. Generalized linear models were used to explore the significance of environmental variables in relation to variability in catch and catch per unit effort (cpue). Squid are fished with jigs in water shallower than 20 m, generally where SST is warmer and Chl a and windspeed are lower. Cpue and monthly catches decreased from 2005 to 2008, followed by a slight increase in 2009. The correlations between fishery and environmental data relate well to fishers' oceanological knowledge, underscoring the potential of incorporating such knowledge into evaluations of the fishery.

Gasalla, M. A., Rodrigues, A. R., and Postuma, F. A. 2010. The trophic role of the squid Loligo plei as a keystone species in the South Brazil Bight ecosystem. – ICES Journal of Marine Science, 67: 1413–1424. The issue of whether loliginid squid can influence the average structure of marine ecosystems in a keystone role, i.e. a strong effect with relatively low biomass, has not yet been examined. Here, the diet of Loligo plei in inner shelf waters of the South Brazil Bight was examined, as a first step, based on the stomach contents of 2200 squid hand-jigged in shallow water (<30 m) and taken as bycatch of shrimp trawlers in deeper water (30–100 m). Diet varied by size, season, and fishing zone. Stomachs were not empty in ∼12%, with more empty during winter. The range of mantle lengths of squid caught by jigging (101–356 mm) appeared to differ from the squid trawled (30–236 mm), and the diet also differed. Food categories recorded in deeper water did not include amphipods or polychaetes, but in both fishing areas, fish were the most common prey. The fish prey identified included Trachurus lathami, small pelagic species, trichiurids, and Merluccius hubbsi. Demersal species, such as Ctenosciaena gracilicirrhus, and flatfish were also present. An ecosystem network model is updated through which a mixed-trophic impact matrix and “keystoneness” indicators were calculated. Loligo plei represents an important link between pelagic and demersal energy pathways, with high indices of keystoneness.

Variações temporais da captura de recursos pesqueiros estão relacionadas à(s): (1) disponibilidade dos mesmos e a outros fatores oceanográficos, (2) respostas dos estoques pesqueiros às remoções geradas pela pesca, (3) alteração na estrutura das comunidades derivadas de ações antrópicas, e (4) mudanças nas decisões dos pescadores, como escolha dos portos de desembarque e evolução do interesse comercial. Sua análise é fundamental para monitorar mudanças ou alterações nas pescarias e nos ecossistemas marinhos. A pesca de cefalópodes loliginídeos (lulas) ocorre em ecossistemas costeiros e de plataforma continental, e representa importância crescente na costa Sudeste do Brasil, onde concentrações significativas de Loligo plei e Loligo sanpaulensis representam recursos pesqueiros costeiros potenciais (Costa & Haimovici, 1990, Pérez, 1999, Gasalla & Marques, 2000). Artesanalmente, as lulas são capturadas no verão, junto a ilhas costeiras, através de linha-de-mão com zangarilhos, em pequenas embarcações. De forma industrial, estes recursos ocorrem como fauna acompanhante ou captura acessória da frota pesqueira, principalmente a de arrasto-de-fundo.