The choice of a suitable sampler for benthic macroinvertebrates in deep rivers

Both chemical and biological methods are used to assess the water quality of rivers. Many standard physical and chemical methods are now established, but biological procedures of comparable accuracy and versatility are still lacking. This is unfortunate because the biological assessment of water quality has several advantages over physical and chemical analyses. Several groups of organisms have been used to assess water quality in rivers and these include Bacteria, Protozoa, Algae, macrophytes, macroinvertebrates and fish. Hellawell (1978) provides an excellent review of the advantages and disadvantages of these groups, and concludes that macroinvertebrates are the most useful for monitoring water quality. Although macroinvertebrates are relatively easy to sample in shallow water (depth < 1m), quantitative sampling poses more problems than qualitative sampling because a large number of replicate sampling units are usually required for accurate estimates of numbers or biomass per unit area. Both qualitative and quantitative sampling are difficult in deep water (depth > 1m). The present paper first considers different types of samplers with emphasis on immediate samplers, and then discusses some problems in choosing a suitable sampler for benthic macroinvertebrates in deep rivers.

Physiological Determinants of Invasive Success Linking Distribution Patterns to Metabolic Physiology in Native and Invasive Blue Mussels (genus Mytilus)

In the early 20th century, a blue mussel species from the Mediterranean invaded the California coast and subsequently out-competed the native species south of Monterey Bay. Like other invasive species, Mytilus galloprovincialis has physiological traits that make it successful in habitats formerly occupied by the native M. trossulus, namely its adaptation to warm sea surface temperatures. This study looks at the current genotype distributions and enzymatic activities of field-acclimatized mussels within the hybrid zone where the species co-occur as well as mussels that have been acclimated for four weeks to different temperature and salinity conditions. In the field-acclimatized and laboratory-acclimated mussels, the native species exhibited significantly higher enzyme rates, which may reflect an evolutionary adaptation to compensate to low habitat temperatures. Indeed, the results of the laboratory acclimation indicate that these differences are genetically based. Whether an acclimation capacity exists may require even longer-term acclimation to different temperatures. Current findings suggest that the further spread of the invasive species is likely to be governed in large measure by the potentially counteracting effects of rising temperatures, which would favor the northerly spread of M. galloprovincialis, and increased winter precipitation, which would favor the persistence of M. trossulus. However, the success of M. galloprovincialis during acclimation to ‘dilute’ salinity (25 ppt) suggests that the invasive species can tolerate a greater salinity range than previously thought. Thus, further investigation is needed to build a comprehensive predictive model of the movement of M. galloprovincialis and the hybrid zone along the California coast.

Age- or length-based methods of growth estimation. What drives the choice?

Based upon a global comparison of over 400 fisheries, the Principal Components Analysis (PCA) methodology was used to identify factors affecting the choice of growth estimation methods. Of the six factors examined, the growth rate (K) and asymptotic length (L8) explained most of the variations. Financial resources, i.e., Gross National Product (GNP), and latitude were also important factors.

Determinants of women's economic participation in the small-scale fisheries sector, Peninsular Malaysia

This paper specifically examines the main determinants of women participation in income-earning activities in Peninsular Malaysian small scale fisheries.

Factors influencing choice of fishing location in Nankumba Peninsula: A case of study of gillnet and chilimira fisheries

This study was carried out to identify factors that influence choice of fishing location and carry out profitability analysis of Chilimira and Gillnet in different fishing locations. A survey using semi-structured questionnaire was administered to 99 Gillnet and 101 Chilimira fishers in Nankumba Peninsula in Mangochi District. The logit model was used to determine the factors influencing choice of fishing location among the fishers. The study showed that 92.1% of Chilimira fishers are operating in offshore areas while 69.7% Gillnet fishers are operating in inshore areas. Chilimira offshore fishers have higher daily average gross margins than their inshore counterparts and Gillnet fishers. However, they incurred more operating costs than the inshore Chilimira and Gillnet fishers. Furthermore, they find their fishing occupation more rewarding as evidenced by the higher returns to labour. The factors that influenced fisher’s choice of fishing location were Age of the fisher, type of fishing vessel and gear, possession of motor sail engine and access to information about previous day’s catch rates. Finally the study concluded that artisanal fishers in Malawi use different criteria in deciding where to fish. The criterion involves a complex interaction of biological, technological, personal and economical factors and time. However, the resource constrained artisanal fisher will need support to enable him exploit offshore fishery resources. Consequently the study recommends that appropriate fishery development interventions by the government and other stakeholders must adapt to the economics and lifestyles driving the artisanal fishers to fish in particular locations and therefore, build on this foundation to improve the existing fishing technologies.

Determinants of small-scale fishermen's income on Oman's Batinah Coast

The small-scale fishing industry of Oman is responsible for almost 90 percent of the total marine fishery production. It is also the main supplier of fish for Omani households. This study analyzes the factors that determine small-scale fishermen’s income on Oman’s Batinah Coast, which has almost 30 percent of Oman’s population and more than one-third of the small-scale fishermen. We find that fishermen’s income here can be explained broadly under four major blocks of variables: geographical region, fishing inputs and catch, socioeconomic and demographic characteristics, and the nature of the relationship with fisheries extension services. In general, the Wilayat (local administrative units) failed to make any significant impact on fishermen’s income. The variable “Fishing inputs and catch,” such as increases in engine power, boat length, weekly catch, and number of weekly trips, positively impacted fishermen’s income while increases in weekly fishing costs, number of crew members, and difficulty in getting ice had a significantly negative effect on the income. Furthermore, socioeconomic and demographic characteristics also contributed significantly in determining the fishermen’s income level. The other important findings were related to extension services. The variables “Fishermen’s exchange of information and cooperation with the ministry” and “Fishermen’s involvement in the extension activities” were found to have positive effects on fishermen’s income levels. Capitalizing on these findings could improve fishermen’s incomes and their lives across the region, as well as nationally.

Vocational education and fisheries

Vocational courses in fisheries are offered in 4 states in India. The technologies in fisheries developed offer good scope for vocational training for self employment. There is an urgent need to have radical revision of the course content to make the students vocationally competent.

Vocational education for the development of knowledge system in fisheries sector

The paper aims to give the concept and functional approach of knowledge system with reference to the fisheries sector. The background and strategies to develop knowledge workers by translating the concept of knowledge system are presented. The job opportunities given in the paper strengthen the need of the development of knowledge workers through vocational education and training. The Vocational Education Programme in the backdrop can be effective both in the formal system of education through different models suggested and through the non-formal system. The modular courses varying from 50 hours and 2-3 weeks to 6 months or one year can be introduced in the formal system as pre-vocational modules (50-h duration) in IX-X classes in vocational institutions, and the non-governmental organizations/Krishi Vigyan Kendras/Indian Council of Agricultural Research may offer occupation-based modules (2-3 weeks to 6 months). The strategic approach for the development of knowledge system highlighting various issues is also suggested.

A wider choice of construction materials for the modern fishing boats

An account of fishing vessel construction materials is given, with information on essential features, and a material account. Materials discussed in detail are steel, wood, aluminium, glass reinforced plastic, and ferro-cement.