Comparisons of Shark Catch Rates on Longlines Using Rope/Steel (Yankee) and Monofilament Gangions

During the months of June through September in 1991 and 1992, 71 shark longlines were fished in the Chesapeake Bight region ofthe U.S. mid-Atlantic coast with a combination of rope/steel (Yankee) and monofilament gangions. A total of 288 sharks were taken on 3,666 monofilament gangions, and 352 sharks were caught on 6,975 Yankee gangions. Catch rates between gear types differed by depth strata, by month, and by species. Analyses were divided between efforts in the nursery ground ofthe sandbar shark, Carcharhinus plumbeus, in Chesapeake Bay and efforts outside the Bay. Mean catch per unit effort (CPUE) ± SE, as sharks caught per 100 hooks fished, was significantly (P<0.05) lower for Yankee gangions. Mean CPUE's for sandbar sharks in the nursery ground were 20.6 ± 3.8 for Yankee gangions and 26.0 ± 3.0 for monofilament gangions, and mean CPUE's for all species combined outside the Bay were 3.7 ± 0.7 for Yankee gangions, and 6.9 ± 1.2 for monofilament gangions.

Artificial Habitats for Fisheries Enhancement in the Australian Region

This paper outlines developments over about 20 years in the construction of and ecological research on artificial reefs, fish aggregation devices (FAD's), and other artificial habitats designed to enhance fish populations and fisheries in the Australian region (including New Zealand and Papua New Guinea). Work was initially carried out on multicomponent reefs using a variety of waste materials, as well as some specially constructed concrete and steel structures. Later studies concentrated on single-component reefs, again mainly using waste materials. Although no definitive conclusions were reached on the relative effectiveness of the different materials used, waste motor vehicle tires and derelict ships were generally judged to be the best all-around materials for single-component reef construction in sheltered estuarine and offshore marine environments, respectively, in this region. FAD's comprising polyvinylchloride pipe sparbuoys (or in some areas polyurethane foam floats) attached to railroad car wheel anchors by polyethylene rope and chain, and supporting attractor drapes of synthetic mesh webbing, also provedtobegenerallysuccessfulin thisarea. Overall conclusions for the Australian region include the predominant use of waste materials in artificial reef construction, which has been primarily aimed at recreational fisheries enhancement; the successful use of FAD's for both recreational and commercial fisheries enhancement; the need for further and better planned research into and monitoring of the effectiveness of both of these enhancement methods; and the need for future research into the effectiveness of unfished "artificial habitat reserves" in enhancing fisheries production from surrounding fished areas.

Estudo do fator de forma de área em reparo com chapa colada em tubulações com furo

Este trabalho tem por finalidade o estudo da resistência à pressão hidrostática do reparo realizado com chapa de aço de baixo carbono, colada com adesivo estrutural à base de epóxi em tubulações de aço com furo. Tubulações de parede fina, sob pressão interna, a tensão na direção longitudinal é a metade da tensão circunferencial do tubo, deste modo, o fator de forma da área do reparo, ou seja, a variação das dimensões da chapa nas direções longitudinal e circunferencial do tubo foi investigado. A influência da força de falha do reparo, quando varia-se a dimensão da chapa nas direções citadas, foram analisadas estatisticamente utilizando-se um planejamento fatorial de experimentos. Altos valores de resistência hidrostática do reparo foram encontrados (em torno de 240 bar) quando comparados com as pressões normais de trabalho (em torno de 70 bar) de uma tubulação similar as utilizadas nos testes. Os resultados da pressão de falha do reparo dos 10 grupos analisados apresentaram desvios padrão pequenos, menor que 12 %, demonstrando a eficiência dos procedimentos adotados na confecção do reparo. Os estudos demonstram a não existência de um fator de forma na resistência do reparo devido a variação nas dimensões da chapa nas direções longitudinal e circunferencial do tubo bem como a alta influência na resistência do reparo quando aumenta a área da chapa. Os resultados apontam para o desenvolvimento de um novo procedimento de reparo de contingência.