Estimations, from tagging experiments, of mortality rates and other parameters respecting yellowfin and skipjack tuna

ENGLISH: In this paper, a method of analysis described by Gulland (1963) has been used to estimate the fishing mortality rates of tagged yellowfin and skipjack tuna for specific areas and years. Fishing mortality rates obtained for tagged tunas will also represent those for the entire population from which the tagged fishes were drawn, provided the assumptions used and corrections made for these analyses are valid. Total mortality rates of tagged fishes have also been computed. These are not assumed to be directly equivalent to the total mortality rates of the untagged populations,since tagged fishes are subject to additional types of attrition. These additional sources of mortality are also examined in this study. SPANISH: En el presente trabajo se ha usado un método de análisis descrito por Gulland (1963), para estimar las tasas de mortalidad de pesca de los atunes aleta amarilla y barrilete marcados en áreas y años específicos. Las tasas de mortalidad de pesca obtenidas en atunes marcados representarán también las de toda la población, de la cual fueron extraídos, previendo que las suposiciones usadas y las correcciones hechas para estos análisis sean válidas. Las tasas de mortalidad total de los peces marcados también han sido computadas. No se supone que éstas sean directamente equivalentes a las tasas de mortalidad total de las poblaciones no marcadas, ya que los peces marcados están sujetos también a otros tipos de pérdida. Estas otras causas de mortalidad son examinadas también en el presente estudio.

An evaluation of Northern Florida Bay as a nursery area for red drum, Sciaenops ocellatus, and other juvenile and small resident fishes.

Red drum is one ofthe most popular species sought by anglers in Florida Bay, yet juveniles are rarely encountered. We evaluated Florida Bay as a nursery area for red drum by sampling for recently-settled late larvae in basin areas within the bay with an epi-benthic sled at six stations in November 2000, and at seven stations during December 2000 through February 2001. In November 2000 we surveyed potential sampling sites in quiet backwaters adjacent to mangroves for juvenile red drum. A total of 202 sites were sampled mainly in northern Florida Bay and adjacent waters with a cast net. We collected only one recently-settled red drum larvae and no juveniles. Obviously the sites that we sampled in Florida Bay and adjacent waters are not nursery habitat for this valuable species. Sled collections were dominated by bay anchovy, Anchoa mitchilli, but densities were biased by one collection. Five small resident species were among the dominant species: rainwater killifish, Lucania parva; dusky pipefish, Syngnathus floridae; dwarf seahorse, Hippocampus zosterae; and clown goby, Microgobius gulosus. Three species that spawn outside Florida Bay in the GulfofMexico were common: pinfish, Lagodon rhomboides; pigfish, Orthopristis chrysoptera; and silver perch, Bairdiella chrysoura. Twenty-seven species were collected with the cast net. Hardhead silversides (Atherinomorus stipes), bay anchovy, tidewater mojarra (Eucinostomus harengulus), silver jenny (Eucinostomus gula), and goldspotted killifish (Floridichthys carpio) were the most common in cast net collections. Although only one red drum was collected, we were able to: (1) identify mesohaline waters from our cast net sites to test our preliminary assessment that mesohaline habitat might be limited in Florida Bay, (2) document the distribution and abundance of fishes collected by cast net that should enhance our understanding of ichthyofauna in the Northern Subdivision ofFlorida Bay and adjacent waters, and (3) from epibenthic sled collections, describe the habitats, abundance and distribution of recently settled larvae/small juveniles/small resident fishes during late fall and winter. This information should be useful to managers and future research. (PDF contains 34 pages)

Symposium on participatory approaches to reservoir fisheries management: issues, challenges and policies. Dambulla, Sri Lanka, 04-06 Oct. 2004. Session I: Community-based fisheries management: experience in other countries

This paper advocates strategies, processes and practices that enable: livelihoods approaches rather than resource-based approaches, ‘direct’ institutional and policy development, rather than ‘project demonstrations’, and support for regional, national and local communications. (Pdf contains 12 pages).

Symposium on participatory approaches to reservoir fisheries management: issues, challenges and policies. Dambulla, Sri Lanka, 04-06 Oct. 2004 Session I. Community-based fisheries management; experience in other countries: presentation on STREAM Vietnam’s experience

Established in early 2002, STREAM Vietnam has so far attained a number of good experiences and lessons in using participatory approaches for its work. The Country Office has been able to link to a wide range of stakeholders, and is working hard to build close relationships amongst them, so that institutional entities can better support the livelihoods of poor aquatic resources users, and support disadvantaged groups of people to improve their living standards by themselves. Reservoir fisheries and co-management are at early stage in Vietnam, but in certain places and industries co-management has brought about successful results by involving proactive participation of communities. Situated on the same continent and having many similarities, the interaction in agriculture and fisheries sector between Vietnam and Sri Lanka has brought the two countries closer. Being members of the STREAM family, there are great opportunities for exchange of experiences and lessons towards sustainable management of reservoir resources. (PDF has 11 pages.)

Lessons from the breeding program of rohu

For the first time in India, selective breeding work has been initiated at the Central Institute of Freshwater Aquaculture, Bhubaneswar, India in collaboration with the Institute of Aquaculture Research (AKVAFORSK), Norway. Rohu has been chosen as the model species because it enjoys the highest consumer preference among Indian major carps (IMC) although its performance was observed to be slower than other IMC. As this was the first ever selection work on any Indian major carp, many procedures and techniques for successful implementation of the programs were standardized (i.e. production of full-sib groups, establishment of model hatchery for selective breeding of carps, rearing of full-sib groups in partitioned nursery ponds, individual tagging with the Passive Integrated Transponder (PIT) tag, communal rearing, sampling, data analysis, field testing and dissemination of improved rohu). After four generations of selection, an average of 17 per cent higher growth per generation was observed in improved rohu.

Conservation Biology of Elasmobranchs

Elasmobranchs are vital and valuable components of the marine biota. From an ecological perspective they occupy the role of top predators within marine food webs, providing a regulatory control that helps balance the ecosystem. From an evolutionary perspective, this group represents an early divergence along the vertebrate line that produced many unusual, but highly successful, adaptations in function and form. From man's perspective, elasmobranchs have been considered both an unavoidable nuisance, and an exploitable fishery resource. A few of the large shark species have earned a dubious notoriety because of sporadic attacks on humans that occur in coastal areas each year worldwide; the hysteria surrounding an encounter with a shark can be costly to the tourist industry. More importantly, elasmobranchs are often considered a detriment to commercial fishing operations; they cause significant economic damage to catches and fishing gear. On the other hand, consumer attitudes have changed concerning many previously unpopular food fishes, including elasmobranchs, and this group of fishes has been increasingly used by both recreational and commercial fishing interests. Many elasmobranchs have become a popular target of recreational fishermen for food and sport because of their abundance, size, and availability in coastal waters. Similarly, commercial fisheries for elasmobranchs have developed or expanded from an increased demand for elasmobranch food products. (PDF file contains 108 pages.)

Responsible fish utilization

These guidelines have been produced to support the implementation of the Code of Conduct for Responsible Fisheries particularly with regard to the need for responsibility in the post– harvest sector of the fish producing industry. The industry that produces fish for food has three major areas of responsibility: to the consumer of the food to ensure that it is safe to eat, is of expected quality and nutritional value, to the resource to ensure that it is not wasted and to the environment to ensure that negative impacts are minimized. In addition the industry has a responsibility to itself to ensure the continued ability of many millions of people throughout the world to earn a gainful living from working within the industry. Article 11.1 of the Code of Conduct for Responsible Fisheries and other related parts of the Code are concerned particularly with these responsibilities. This publication provides annotation to and guidance on these articles to assist those charged with implementation of the Code to identify possible courses of action necessary to ensure that the industry is conducted in a sustainable manner. (PDF contains 42 pages)

Fisheries marketing systems and consumer preferences in Puttalam District Sri-Lanka

The aim of this study was to understand the current and historic market situation for inland fish and it’s substitutes in order to identify which of the various production opportunities presented by the seasonal tank resource might have greatest relevance for marginal communities in the Dry-zone. Regional and sub-regional market networks for fish and meat products were investigated, ranking and scoring exercises used to characterise consumer demand in rain-fed areas of North West Province and secondary data sources were used to assess historic patterns of demand and supply [PDF contains 57 pages]

Zum tierschutzgerechten Betäuben und Töten von Aal

Slaughtering of eels should be done not only under animal welfare aspects but as well under consumer protection and economical aspects with respect to technical feasibility. Methods must be practicable for enterprises slaughtering quantities of several kilograms up to several tons per day. Most methods applied up to now in whole Europe were (are) not in accordance with animal welfare mainly due to lacking prescriptions and alternative methods. The great number of experiments carried out within the frame of this project demonstrates the difficulties to combine optimal welfare demands with economical and technical fesibility aspects in one method. Measurements of EEG (electroencephalogram) and ECG (electrocardiogram) have shown that the method laid down in the german legislation does not perfectly stun all eels. This method was improved by applying a „prestun“ with 220 V for 1sec., followed by a 5 min phase at 45 V to prolongue the time of unconsciousness after the stun. Inflating nitrogen gas into the stunning bath additionally causes asphyxia during the stun. By this method 93% of the eels were stunned or even killed. Applying 220 V for bigger batches of eels (~400 kg) will cause big problems with the energy supply. Therefore this method is restricted to batches of 20 - 50 kg. The method laid down in the german legislation probably can be improved. Eels were stunned successfully without water, avoiding the problems of regional differences in the conductivity of the water. Other types of current and other frequencies and a combination of both should be tested as well as alternative electrode geometries also with respect to blood spots which occasionally occurred in the muscles preferably of bigger eels (>800 g). For the time being the method laid down in the german legislation is a reasonable compromise and under animal welfare aspects represents a considerable improvement.

Relative importance of Deep Creek Lake to other areas in respect to certain recreational and economic aspects

Presents a review of the recreational values and economic importance of Maryland Fishing waters. (PDF contains 5 pages)

The effect of traditional handling, processing and storage methods on the quality of dried fish in small scale fisheries in Nigeria

Most of the fish marketed throughout Nigeria are in either smoked or dried form. The technological requirement for other forms of preservation like chilling and freezing cannot be afforded by the small scale fisher folk. Considerable quantities of fish processed for distant consumer markets are lost at handling, processing, storage and marketing stages. Significant losses occur through infestation by mites, insects, fungal infestation and fragmentation during transportation. This paper attempts to describe the effect of these losses on fish quality and suggests methods of protecting fish from agents of deterioration

Assessment of consumer acceptance of kilishi of African carp (Labeo coubie Rueppell) and Elephant snout (Hyperopisus bebe occidentalis, Guenther)

This study was carried out to assess consumers' acceptance of kilishi prepared from Labeo coubie and Hyperopisus bebe occidentalis in Sokoto. The organoleptic properties (texture, odour, taste and flavour) of kilishi in its fresh form and under storage for 16 weeks were determined. The mean scores for the organoleptic assessment (6.90 and 7.19 for kilishi of Labeo and Hyperopisus respectively) showed that fish kilishi was highly acceptable. Hyperopisus kilishi recorded slightly higher mean scores for the tested organoleptic properties. The declining pattern of the sensory assessment scores with length of storage indicated that the optimum storage period under the room temperature for kilishi made from the experimental fish species in the study area was 6-8 weeks. Further research on appropriate storage methods is desirable. However, preparation of fish kilishi could be explored as alternative preservation technique to reduce fish spoilage especially during the glut in supply and to diversify fish products

Tastes and odours in potable water:perception versus reality

Tastes and odours are amongst the few water quality standards immediately apparent to a consumer and, as a result, account for most consumer complaints about water quality. Although taste and odour problems can arise from a great many sources, from an operational point of view they are either ”predictable” or ”unpredictable”. The former - which include problems related to actinomycete and algal growth - have a tendency to occur in certain types of water under certain combinations of conditions, whereas the latter - typically chemical spills - can occur anywhere. Long-term control is one option for predictable problems, although biomanipulation on a large scale has had utile success. Detection and avoidance is a more practicable option for both predictable and unpredictable problems, particularly if the distribution network can be serviced from other sources. Where these are not feasible, then water treatment, typically using activated carbon, is possible. In general there is a reasonable understanding of what compounds cause taste and odour problems, and how to treat these. An efficient taste and odour control programme therefore relies ultimately on good management of existing resources. However, a number of problems lie outside the remit of water supply companies and will require more fundamental regulation of activities in the catchment.