A modeling approach to identify optimal habitat and suitable fishing grounds for neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean

We developed a habitat suitability index (HSI) model to understand and identify the optimal habitat and potential fishing grounds for neon f lying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean. Remote sensing data, including sea surface temperature, sea surface salinity, sea surface height, and chlorophyll-a concentrations, as well as fishery data from Chinese mainland squid f leets in the main fishing ground (150–165°E longitude) from August to October, from 1999 to 2004, were used. The HSI model was validated by using fishery data from 2005. The arithmetic mean modeling with three of the environmental variables—sea surface temperature, sea surface height anomaly, and chlorophyll- a concentrations—was defined as the most parsimonious HSI model. In 2005, monthly HSI values >0.6 coincided with productive fishing grounds and high fishing effort from August to October. This result implies that the model can reliably predict potential f ishing grounds for O. bartramii. Because spatially explicit fisheries and environmental data are becoming readily available, it is feasible to develop a dynamic, near real-time habitat model for improving the process of identifying potential fishing areas for and optimal habitats of neon flying squid.

New information from fish diets on the importance of glassy flying squid (Hyaloteuthis pelagica) (Teuthoidea: Ommastrephidae) in the epipelagic cephalopod community of the tropical Atlantic Ocean

Squids of the family Ommastrephidae are a vital part of marine food webs and support major fisheries around the world. They are widely distributed in the open ocean, where they are among the most abundant in number and biomass of nektonic epipelagic organisms. In turn, seven of the 11 genera of this family (Dosidicus, Illex, Martialia, Nototodarus, Ommastrephes, Sthenoteuthis, and Todarodes) are heavily preyed upon by top marine predators, i.e., birds, mammals, and fish, and currently support fisheries in both neritic and oceanic waters (Roper and Sweeney, 1984; Rodhouse, 1997). Their commercial importance has made the large ommastrephids the target of many scientific investigations and their biology is consequently reasonably well-known (Nigmatullin et al., 2001; Zuyev et al., 2002; Bower and Ichii, 2005). In contrast, much less information is available on the biology and ecological role of the smaller, unexploited species of ommastrephids (e.g., Eucleoteuthis, Hyaloteuthis, Ornithoteuthis, and Todaropsis).

Experiments in gear configuration to reduce bycatch in an estuarine squid-trawl fishery

Three experiments were performed in an estuarine squid-trawl fishery in New South Wales, Australia, to test modifications to trawl nets. Lateral mesh openings were experimentally increased and physical bycatch reduction devices (BRDs) were placed in codends. These modifications aimed to reduce nontargeted catches of fish, while maintaining catches of the targeted broad squid (Photololigo etheridgei) and bottle squid (Loliolus noctiluca). Compared to conventional codends made with 41-mm diamond mesh, codends made with different posterior circumferences and larger 45-mm mesh had no significant effect on the catches of any species. The best performing configurations involved the installation of BRDs designed to separate organisms according to differences in behavior. In particular, versions of a composite square-mesh panel reduced the total weight of bycatch by up to 71% and there was no significant effect on the catches of squid. The results are discussed in terms of the probable differences in behavior between fish and squid in codends. After this study, a square-mesh panel BRD was voluntarily adopted throughout the fishery.

Tagging studies on the jumbo squid (Dosidicus gigas) in the Gulf of California, Mexico

Dosidicus gigas, the only species in the genus Dosidicus, is commonly known as the jumbo squid, jumbo flying squid (FAO, see Roper et al., 1984), or Humboldt squid. It is the largest ommastrephid squid and is endemic to the Eastern Pacific, ranging from northern California to southern Chile and to 140oW at the equator (Nesis, 1983; Nigmatullin, et al., 2001). During the last two decades it has become an extremely important fisheries resource in the Gulf of California (Ehrhardt et al., 1983; Morales-Bojórquez et al., 2001), around the Costa Rica Dome (Ichii et al., 2002) and off Peru (Taipe et al., 2001). It is also an active predator that undoubtedly has an important impact on local ecology in areas where it is abundant (Ehrhardt et al., 1983; Nesis, 1983; Nigmatullin et al., 2001; Markaida and Sosa-Nishizaki, 2003).

Diet of the minimal armhook squid (Berryteuthis anonychus) (Cephalopoda: Gonatidae) in the northeast Pacific during spring

The stomach contents of the minimal armhook squid (Berryteuthis anonychus) were examined for 338 specimens captured in the northeast Pacific during May 1999. The specimens were collected at seven stations between 145−165°W and 39−49°N and ranged in mantle length from 10.3 to 102.2 mm. Their diet comprised seven major prey groups (copepods, chaetognaths, amphipods, euphausiids, ostracods, unidentified fish, and unidentified gelatinous prey) and was dominated by copepods and chaetognaths. Copepod prey comprised four genera, and 86% by number of the copepods were from the genus Neocalanus. Neocalanus cristatus was the most abundant prey taxa, composing 50% by mass and 35% by number of the total diet. Parasagitta elegans (Chaetognatha) occurred in more stomachs (47%) than any other prey taxon. Amphipods occurred in 19% of the stomachs but composed only 5% by number and 3% by mass of the total prey consumed. The four remaining prey groups (euphausiids, ostracods, unidentified fish, and unidentified gelatinous prey) together composed <2% by mass and <1% by number of the diet. There was no major change in the diet through the size range of squid examined and no evidence of cannibalism or predation on other cephalopod species.

Survival rates of rays discarded by the bottom trawl squid fishery off the Falkland Islands

Waters off the Falkland Islands are subject to a specialized multispecies ray fishery and were first fished by a Korean fleet in 1989. More than twenty different rajid species have been recorded from catches around the islands, and five species accounted for 87.04% of the total catch during 1993−2002. Catches peaked in 1993 at 8523 metric tons, and specific fishing licenses — R (second season) and F (first season) — were first introduced in 1994 and in 1995, respectively (Agnew et al. 2000; Falkland Islands Government, 2002; Wakeford et al., in press).

Cephalopod fishery at Kakinada along the east coast of India: Resource characteristics and stock assessment of Loligo duvauceli ·

At Kakinada along the east coast of India, cephalopods were exploited by trawls. Fishery occurred round the year with peak during August-October. Peak abundance and fishery of cuttlefishes coincides with this period, whereas for squids it is during March-May. Cephalopod production continued to increase initially with fishing effort, until 1995, but declined thereafter despite increased fishing effort and expansion of fishing to deeper waters. Fishery, growth, mortality, recruitment pattern and exploitation rates of Loligo duvauceli were studied. Nearly 97% of their catch was by zero year groups. They attain sexual maturity and spawn during the first year itself. Spawning occurred round the year with peak during December-February. Exploitation rate of the species is large, 0.741 compared to Emax (0.44). This indicated that their stock is under heavy fishing pressure and subjected to over-exploitation. Stock also exhibited declining trend over the years during 1995-'99. These necessitate immediate attention to avoid coHapse of the stock and fishery.