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).

The relationships between fish assemblages and the amount of bottom horizontal beam exposed at California oil platforms: fish habitat preferences at man-made platforms and (by inference) at natural reefs

Between 1995 and 2002, we surveyed fish assemblages at seven oil platforms off southern and central California using the manned research submersible Delta. At each platform, there is a large horizontal beam situated at or near the sea floor. In some instances, shells and sediment have buried this beam and in other instances it is partially or completely exposed. We found that fish species responded in various ways to the amount of exposure of the beam. A few species, such as blackeye goby (Rhinogobiops nicholsii), greenstriped rockfish (Sebastes elongatus), and pink seaperch (Zalembius rosaceus) tended to avoid the beam. However, many species that typically associate with natural rocky outcrops, such as bocaccio (S. paucispinis), cowcod (S. levis), copper (S. caurinus), greenblotched (S. rosenblatti), pinkrose (S. simulator) and vermilion (S. miniatus) rockfishes, were found most often where the beam was exposed. In particular, a group of species (e.g., bocaccio, cowcod, blue (Sebastes mystinus), and vermilion rockfishes) called here the “sheltering habitat” guild, lived primarily where the beam was exposed and formed a crevice. This work demonstrates that the presence of sheltering sites is important in determining the species composition of man-made reefs and, likely, natural reefs. This research also indicates that adding structures that form sheltering sites in and around decommissioned platforms will likely lead to higher densities of many species typical of hard and complex structure.

How much does the fishery at Apo Island benefit from spillover of adult fish from the adjacent marine reserve?

The contribution of the no-take marine reserve at Apo Island, Philippines, to local fishery yield through “spillover” (net export of adult fish) was estimated. Spatial patterns of fishing effort, yield, and catch rates around Apo Island were documented daily in 2003−2004. Catch rates were higher near the reserve (by a factor of 1.1 to 2.0), but fishing effort was often lowest there. Higher catch rates near the reserve were more likely due to spillover than to low fishing intensity. Lower fishing effort near the reserve may have been due to 1) weather patterns, 2) traditional importance of other fishing grounds, 3) high variability in catch rates, 4) lower market value of target species, and 5) social pressures. The yield taken near the reserve was only 10% of the total yield, but the actual spillover contribution was probably much less than this. This study is one of the few to estimate the spillover contribution to overall yield and to document the responses of fishermen to spil

Estimating the encounter rate of Atlantic capelin (Mallotus villosus) with fish eggs, based on stomach content analysis

The number of pelagic fish eggs (cod and cunner) found in stomachs of capelin (Mallotus villosus) sampled in coastal Newfoundland was used to estimate the encounter rates between capelin and prey, and thus the effective volume swept by capelin. Fish eggs were found in 4−8% of capelin stomachs, represented an average of 1% of prey by numbers, and their abundance increased as relative stomach fullness decreased. The average number of eggs per stomach doubled for each 5-cm increase in length of capelin. The effective volume swept for eggs by capelin ranged from 0.04 to 0.84 m3/h—a rate that implies either very slow capelin swimming speeds (<1 cm/s) or that fish eggs are not strongly selected as prey. The predation rate estimated from stomach contents was higher than that predicted from laboratory studies of feeding pelagic fish and lower than that predicted by a simple foraging model. It remains uncertain whether capelin play an important regulatory role in the dynamics of early life stages of other fish.

Precision and accuracy of fish length measurements obtained with two visual underwater methods

During the VITAL cruise in the Bay of Biscay in summer 2002, two devices for measuring the length of swimming fish were tested: 1) a mechanical crown that emitted a pair of parallel laser beams and that was mounted on the main camera and 2) an underwater auto-focus video camera. The precision and accuracy of these devices were compared and the various sources of measurement errors were estimated by repeatedly measuring fixed and mobile objects and live fish. It was found that fish mobility is the main source of error for these devices because they require that the objects to be measured are perpendicular to the field of vision. The best performance was obtained with the laser method where a video-replay of laser spots (projected on fish bodies) carrying real-time size information was used. The auto-focus system performed poorly because of a delay in obtaining focus and because of some technical problems.

The effect of predation (current and historical) by humpback whales (Megaptera novaeangliae) on fish abundance near Kodiak Island, Alaska

Humpback whales (Megaptera novaeangliae) are significant marine consumers. To examine the potential effect of predation by humpback whales, consumption (kg of prey daily) and prey removal (kg of prey annually) were modeled for a current and historic feeding aggregation of humpback whales off northeastern Kodiak Island, Alaska. A current prey biomass removal rate was modeled by using an estimate of the 2002 humpback whale abundance. A historic rate of removal was modeled from a prewhaling abundance estimate (population size prior to 1926). Two provisional humpback whale diets were simulated in order to model consumption rate. One diet was based on the stomach contents of whales that were commercially harvested from Port Hobron whaling station in Kodiak, Alaska, between 1926 and 1937, and the second diet, based on local prey availability as determined by fish surveys conducted within the study area, was used to model consumption rate by the historic population. The latter diet was also used to model consumption by the current population and to project a consumption rate if the current population were to grow to reach the historic population size. Models of these simulated diets showed that the current population likely removes nearly 8.83

Fish assemblages found in tidal-creek and seagrass habitats in the Suwannee River estuary

Fish assemblages were investigated in tidal-creek and seagrass habitats in the Suwannee River estuary, Florida. A total of 91,571 fish representing 43 families were collected in monthly seine samples from January 1997 to December 1999. Tidal creeks supported greater densities of fish (3.89 fish/m2; 83% of total) than did seagrass habitats (0.93 fish/m2). We identified three distinct fish assemblages in each habitat: winter−spring, summer, and fall. Pinfish (Lagodon rhomboides), pigfish (Orthopristis chrysoptera), and syngnathids characterized seagrass assemblages, whereas spot (Leiostomus xanthurus), bay anchovy (Anchoa mitchilli), silversides (Menidia spp.), mojarras (Eucinostomus spp.), and fundulids characterized tidal-creek habitats. Important recreational and commercial species such as striped mullet (Mugil cephalus) and red drum (Sciaenops ocellatus) were found primarily in tidal creeks and were among the top 13 taxa in the fish assemblages found in the tidal-creek habitats. Tidal-creek and seagrass habitats in the Suwannee River estuary were found to support diverse fish assemblages. Seasonal patterns in occurrence, which were found to be associated with recruitment of early-life-history stages, were observed for many of the fish species.

Changes in consumer tastes in the demand for fish and meat in Malaysia

In this article the demand for fish and its substitute was estimated using a very flexible demand function, the Almost Ideal Demand System (AIDS) developed by Deaton and Muelllbaeur (1980), incorporating the habit formation variable to measure the impact of the changes in tastes in comsumer demand for fish and meat products from 1960 to 1990 in Malaysia. Information on price and income elasticities for these meat groups was also obtained. To incorporate consumption habit variables, the dynamic translating procedure proposed by Pollak (1970) and Pollak and Wales (1981) has been adopted. The overall results of the maximum likelihood estimates of the dynamic AIDS model are quite good where 19 of 30 coefficients are significantly different from zero and the minimum budget shares, the constant, are between zero and one for each meat type. Consumers tend to purchase and consume fish, chicken, and pork almost daily. Beef and mutton are only consumed occassionally since they are relatively more expensive. This finding is consistent with the trend observed in the per capita consumption and budget share where fish, chicken, and pork tended to dominate over beef and mutton from 1960 to 1990.

Fish for the poor under a rising global demand and changing fishery regime

In the past, agricultural researchers tended to ignore the fisheries factor in global food and nutritional security. However, the role of fish is becoming critical as a result of changes in fisheries regimes, income distribution, demand and increasing international trade. Fish has become the fastest growing food commodity in international trade and this is raising concern for the supply of fish for poorer people. As a result, the impact of international trade regimes on fish supply and demand, and the consequences on the availability of fish for developing countries need to be studied. Policies aimed at increasing export earnings are in conflict with those aimed at increasing food security in third world countries. Fisheries policy research will need to focus on three primary areas which have an impact on the marginal and poorer communities of developing countries: increased international demand for low-value fish on the supply of poorer countries; improved aquaculture technologies and productivity on poorer and marginal farmers; and land and water allocation policy on productivity, food security and sustainability across farm, fishery and related sectors. The key to local food security is in the integration of agriculture, aquaculture and natural resources but an important focus on fisheries policy research will be to look at the linkages between societal, economic and natural systems in order to develop adequate and flexible solutions to achieve sustainable use of aquatic resources systems.

Fish consumption pattern in major freshwater fisheries provinces of Cambodia

Production and consumption of fish were estimated for a one year period during 1995-96 using a sample of 5 117 households. The sample was taken from a study area covering 83 sample communes in 51 fishing districts belonging to eight freshwater fisheries provinces. About 39% of households in fishing dependent communities were actively involved in fishing. Of the total fishing households, 14% took part in commercial fishing using middle-scale fishing gear. Average annual catch per household for middle-scale and family fishing was 3 319 kg and 647 kg, respectively. Nearly 40% of the fish catch was consumed within the communes. The per capita consumption of fresh fish by fishing households (49.7 kg/yr) was higher than that of non-fishing households (39.9 kg/yr). Including processed fish, the total fish consumption by the fishing dependent communes was estimated at 75.6 kg per capita per annum. Given this high rate of fish consumption, development interventions must consider the role of fisheries in ensuring a sustainable livelihood and food security to Cambodia's growing population.

Occurrence and distribution of fish species off Yemen (Gulf of Aden and Arabian Sea)

The species list is drawn from an analysis of catches taken by Sumalian and Russian trawlers in the Gulf of Aden and the Arabian Sea between 1985 and 1990. The southern coastline of the Republic of Yemen has been divided into 7 areas, including waters around Socotra Island. The average depth of each trawl was recorded in 50 m increments. Non-appearance of the species in the area does not mean that the species do not occur in that area or depth, merely that it was not recorded in any of the samples analyzed. Specimens that could not be identified to species level have been excluded. A total of 195 species from 75 families was recorded and is summarized. Most of the identification of species was from FAO species identification literature. Confirmation of some species and usage of common names is from ICLARM's FishBase and Al Sedfy, et al. (1982).

Biodiversity of estuarine fish faunas in West Africa

In West Africa (between Ivory Coast and Sénégal), estuarine environments vary from lagoons to high discharge rivers to inverse hypersaline estuaries. This results in a high diversity of estuarine fish species, with an important turnover and a core of ubiquitous species. The species richness of a given estuary depends on the combination of hydrological factors (marine or freshwater dominance) and biogeography (continental biogeographic regions). The catch rate is higher in lagoons and inverse estuaries than in normal estuaries, which can be explained by the predominance of small juveniles in the latter. Clupeids are the most abundant fishes all over the region, but different systems have different dominant species. Assessing the functioning of West-African estuaries provides useful comparisons to Asian estuarine systems.

Composição elementar corporal, desbalanço alimentar e reciclagem de nutrientes em peixes de um riacho costeiro de Mata Atlântica

No presente estudo foi avaliada a variação na dieta e na composição elementar corporal (C:N:P) de oito espécies de peixes que coocorrem em dois trechos de um riacho. Além disso, foram investigadas as diferenças na demanda e excreção de nutrientes por duas espécies de Loricariidae, sendo uma nativa (Hypostomus punctatus) e a outra não nativa (Parotocinclus maculicauda). As coletas foram realizadas no rio Ubatiba, através de pesca elétrica em diferentes meses entre os anos de 2010 e 2012. A partir da análise alimentar, observamos que as espécies apresentaram variação na dieta entre as localidades, com exceção das duas espécies de Characidium. Apesar destas variações, o presente estudo corroborou a hipótese de homeostase estequiométrica corporal. A exceção foi a espécie Hoplias malabaricus que apresentou variação na concentração elementar corporal e alto desbalanço alimentar entre as localidades, sendo as diferenças mais acentuadas na área aberta. Analisando as diferenças na demanda nutricional dos Loricariidae verificamos uma maior concentração corporal de carbono e nitrogênio para a espécie nativa e maior de fósforo na espécie não nativa, sendo essa diferença confirmada por um maior consumo de fósforo pela espécie não nativa. A análise da excreção revelou que a espécie nativa excreta mais nitrogênio e fósforo que a não nativa. Sendo assim, os resultados sugerem que a espécie não nativa apresenta uma requisição de fósforo maior do que a nativa. Logo, ambientes com altas concentrações de nutrientes, tal como o riacho estudado, podem favorecer o estabelecimento desta espécie

Integrating fish into seasonally flooded rice fields: on-farm trials in Assam, India

In the State of Assam, floodplains cover 2.6 million ha of area that is traditionally rice growing. The ecosystem in the rice-growing areas has undergone major changes as a result of various developmental activities and adoption of modern farming technology. Rice fields were once the major source of fish for the rural farmers. There has been a sharp decline in fish population in rice field leading to a chronic shortage of fish in the State and a deterioration of the rice ecosystem. This paper describes two on-farm experiments for integrating rice cultivation and fish production with the intent of contributing to the understanding of how raising fish can improve rice yields, riceecosystems and farm incomes.