Biology, Oceanography, and Fisheries of the North Pacific Transition Zone and Subarctic Frontal Zone: Papers from the North Pacific Transition Zone Workshop, Honolulu, Hawaii, 9-11 May 1988

In the past few years, large-scale, high-seas driftnet fishing has sparked intense debate and political conflict in many oceanic regions. In the Pacific Ocean the driftnet controversy first emerged in the North Pacific transition zone and subarctic frontal zone, where driftnet vessels from Japan, the Republic of Korea, and Taiwan pursue their target species of neon flying squid. Other North Pacific driftnet fleets from Japan and Taiwan target stocks of tunas and billfishes. Both types of driftnet fishing incidentally kill valued non-target species of marine life, including fish, mammals, birds, and turtles. In response to public concerns about driftnet fishing, government scientists began early on to assemble available information and consider what new data were required to assess impacts on North Pacific marine resources and the broader pelagic ecosystem. Accordingly, a workshop was convened at the NMFS Honolulu Laboratory in May 1988 to review current information on the biology, oceanography, and fisheries of the North Pacific transition zone and subarctic frontal zone. The workshop participants, from the United States and Canada, also developed a strategic plan to guide NMFS in developing a program of driftnet fishery research and impact assessment. This volume contains a selection of scientific review papers presented at the 1988 Honolulu workshop. The papers represent part of the small kernel of information available then, prior to the expansion of cooperative international scientific programs. Subsequent driftnet fishery monitoring and research by the United States, Canada, Japan, Korea, and Taiwan have added much new data. Nevertheless, this collection of papers provides a historical perspective and contains useful information not readily available elsewhere. (PDF file contains 118 pages.)

(Report of the) Institute of Marine Biology and Oceanography, Fourah Bay College, University of Sierra Leone

Details are given of the Institute and its activities, in particular the research projects being undertaken. These include studies on the marine molluscs of Sierra Leone, the cockle fishery, a preliminary investigation on the fouling organisms affecting the raft-cultured oyster populations, larval oyster ecology in relation to oyster culture, preliminary studies on the reproductive cycle of the mangrove oyster (Crassostrea tulipa), and catch composition of fishes taken by beach-seines at Lumley (Freetown). Records of the west African manatee (Trichechus senegalensis) are noted.

Biology of the mullet species occurring in the estuaries of Freetown Peninsula

This brief paper gives some notes on the geographical distribution and salinity tolerances of some Mugil species occurring in the Black-Johnson estuary, Sierra Leone

Marine biology of the Sierra Leone River Estuary. 1. The physical environment

The Sierra Leone River Estuary is a relatively young drowned river valley, it is shallow except for a deep channel which passes close to the Freetown shoreline. The upper reaches merge into a network of creeks and channels fringed by large areas of mangrove swamps. It is a tidal estuary of the semi-mixed type with the saline oceanic water entering it on a diurnal cycle. The climate of Sierra Leone is marked by a very distinct change between a very wet rainy season and a dry season. The tidal range of the Estuary (spring 3.03m; neap 2.28m) does not impede normal use of the harbour. The tidal variations can be felt as far as 42 miles inland along the water courses of the Sierra Leone River and its tributaries. The volume of fresh water entering the Estuary is large during the rainy season and greatly reduced during the dry season. Consequently there is a marked fall in salinity during the rainy season and higher salinities due to the marine influence prevailing during the dry season. The nature of the shores and bottom, the hydrography and chemistry of the estuarine system have been outlined in relation to the prevailing climatic conditions.

Feeding Ecology of the Franciscana (Pontoporia blainvillei) In Marine And Estuarine Waters Of Argentina

Stomach contents of 110 franciscanas (Pontoporia blainvillei), from northern Argentina were analysed in order to improve our knowledge about the feeding habits of this species and to better characterise the lactation period. The samples included calves, juveniles and adults of both sexes. Evidence of predation by franciscanas is seen at a very young age (2.5-3 months), with a transition diet composed by both milk and solid food, mainly represented by crustaceans. Weaning seems to begin by April, when franciscanas are about 6-7 months old. Franciscanas inhabiting two different habitats were analysed in this study: a brackish water estuary and an adjacent marine coastal system. The diet of Pontoporia blainvillei in northern Argentina was composed by a total of 26 prey species: 20 teleosts, 4 crustaceans and 2 cephalopods. Based on the Index of Relative Importance (IRI) the main prey species were Cynoscion guatucupa, Micropogonias furnieri, Loligo sanpaulensis and Urophycis brasiliensis. Estuarine franciscanas preyed mainly on Micropogonias furnieri (dominant species), Cynoscion guatucupa, Odonthestes argentinensis and Macrodon ancylodon, while dolphins from marine areas preyed mainly on Cynoscion guatucupa (dominant species), Loligo sanpaulensis and Urophycis brasiliensis. Our results confirm that franciscanas prey mainly on juvenile fish (< 8cm) and small loliginid squids, in close agreement with previous results obtained in southern Brazil and Uruguay. Qualitative and quantitative differences observed in the diet of dolphins from each habitat emphasise the need to discriminate between samples from different habitats and environmental parameters. SPANISH: Se analizaron 110 contenidos estomacales de franciscanas (Pontoporia blainvillei) provenientes de la costa norte de Argentina, para extender en conocimiento sobre su dieta y caracterizar la lactancia. Las muestras incluyeron cachorros, juveniles y adultos de ambos sexos. Las primeras etapas de predación se inician a muy temprana edad (2,5-3 meses), presentando una dieta de transición compuesta tanto por leche como por presas sólidas, principalmente crustáceos; el destete se iniciaría a partir de abril, a una edad estimada entre 6 y 7 meses. Las franciscanas estudiadas provienen de dos habitats diferentes: un área estuarial de baja salinidad y la region marina adyacente. La dieta de Pontoporia blainvillei de Argentina estuvo compuesta por un total de 26 especies: 20 teleósteos, 4 crustáceos y 2 cefalópodos. Basados en el Indice de Importancia Relativa (IIR), las presas más importantes fueron Cynoscion guatucupa, Micropogonias furnieri, Loligo sanpaulensis y Urophycis brasiliensis. Las franciscanas provenientes del área estuarial predaron principalmente sobre Micropogonias furnieri (especie dominante), Cynoscion guatucupa, Odonthestes argentinensis y Macrodon ancylodon, mientras que los delfines marinos predaron sobre Cynoscion guatucupa (especie dominante), Loligo sanpaulensis y Urophycis brasiliensis. Nuestros resultados confirman que la franciscana preda sobre peces juveniles (< 8cm) y pequeños calamares Loliginidae, coincidiendo con resultados previos obtenidos en el sur del Brasil y Uruguay. Las diferencias cualitativas y cuantitativas observadas en la dieta de cada uno de las áreas analizadas, nos sugieren que los futuros estudios sobre ecología trófica de la franciscana deberían discriminarse de acuerdo al origen de los ejemplares y a la tipificación del ambiente.

Cruise Report 64-S-2 - Shrimp

(PDF contains 7 pages.)

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Southwest): Amphipods

(PDF contains 24 pages)

El alga invasora Undaria pinnatifida (Harvey) Suringar en la Ría Deseado (Patagonia austral, Argentina): ciclo del esporofito y factores ambientales determinantes de su distribución

Undaria pinnatifida was registered in Ría Deseado (47º45´S, 65º55´W _ southern Patagonia) by the first time in spring 2005, colonizing the intertidal and shallow subtidal. A seasonal survey in 2006 showed that U. pinnatifida was established in a sheltered zone inside the estuary, along a coastal fringe of 8 km between Punta Cascajo and Cañadón del Puerto. This continuous distribution was only interrupted in the mouth of canyons that flow into Ría Deseado, where the bottom is conformed by mud and sand. The sporophytes were mainly found colonizing the rocky bottom in the lower intertidal, bordering the Macrocystis pyrifera population. The highest density and biomass of sporophytes (12.13 ind. m-2; 254.60 g m-2) were registered during spring, when the population was mainly conformed by individuals of medium sizes. The lowest density and biomass (0.33 ind. m-2; 5.69 g m-2) were registered in autumn. Juvenile sporophytes recruited throughout the year, but presented the highest percentage in the population during autumn and winter. First mature sporophytes appeared in spring and attained their maximum size in summer. After this, the sprophytes decayed and disappeared. Environmental factors such as rocky bottoms availability and water transparency may be the main factors determining the sporophytes distribution in Ría Deseado. The field experiment point out that M. pyrifera population is an important factor controlling the dispersion of U. pinnatifida towards the subtidal. SPANISH: Undaria pinnatifida fue registrada en la Ría Deseado (47º45´ S, 65º55´ W _ Patagonia austral) durante la primavera de 2005, colonizando el intermareal y submareal somero. Los relevamientos estacionales realizados durante el 2006, revelaron que U. pinnatifida se encontró establecida en una zona protegida en el interior de la ría, ocupando una franja costera de aproximadamente 8 km de largo entre Punta Cascajo y el Cañadón del Puerto. Esta distribución casi continua sólo presentó algunas interrupciones en la boca de los cañadones que desembocan en la ría, donde el fondo predominante es de tipo areno-fangoso. Los esporofitos de U. pinnatifida ocuparon preferentemente el fondo rocoso del intermareal inferior, limitando con la población de Macrocystis pyrifera. La densidad y biomasa más altas de esporofitos (12,13 ind. m-2; 254,60 g m-2) fueron registradas en primavera, cuando la población se encontró compuesta principalmente por individuos de tallas intermedias. La densidad y biomasa más bajas (0,33 ind. m-2; 5,69 g m-2) fueron registradas durante el otoño. Los esporofitos juveniles se reclutaron a lo largo de todo el año, pero alcanzaron su mayor proporción en la población durante el otoño y el invierno. Los esporofitos reproductivamente maduros aparecieron durante la primavera y alcanzaron su talla máxima durante el verano, luego del cual comenzaron a deteriorarse y a desaparecer. Factores como la disponibilidad de fondos rocosos y la transparencia de las aguas podrían actuar como los principales factores determinantes de su distribución en la ría. El experimento de campo realizado revela que los bosques de M. pyrifera actúan también como un importante factor de control, limitando la dispersión de U. pinnatifida hacia el submareal.

Effects of El Niño–Southern Oscillation events on catches of Bigeye Tuna (Thunnus obesus) in the eastern Indian Ocean off Java

The effects of El Niño–Southern Oscillation events on catches of Bigeye Tuna (Thunnus obesus) in the eastern Indian Ocean (EIO) off Java were evaluated through the use of remotely sensed environmental data (sea-surface-height anomaly [SSHA], sea-surface temperature [SST], and chlorophyll a concentration), and Bigeye Tuna catch data. Analyses were conducted for the period of 1997–2000, which included the 1997–98 El Niño and 1999–2000 La Niña events. The empirical orthogonal function (EOF) was applied to examine oceanographic parameters quantitatively. The relationship of those parameters to variations in catch distribution of Bigeye Tuna was explored with a generalized additive model (GAM). The mean hook rate was 0.67 during El Niño and 0.44 during La Niña, and catches were high where SSHA ranged from –21 to 5 cm, SST ranged from 24°C to 27.5°C, and chlorophyll-a concentrations ranged from 0.04 to 0.16 mg m–3. The EOF analysis confirmed that the 1997–98 El Niño affected oceanographic conditions in the EIO off Java. The GAM results indicated that SST was better than the other environmental factors (SSHA and chlorophyll-a concentration) as an oceanographic predictor of Bigeye Tuna catches in the region. According to the GAM predictions, the highest probabilities (70–80%) for Bigeye Tuna catch in 1997–2000 occurred during oceanographic conditions during the 1997–98 El Niño event.

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Northwest): Amphipods

This report wi11 focus largely on the suborders Gammaridea, Caprellidea, and Hyperiidea because of their importance in coastal areas of the northeast Pacific Ocean. (PDF contains 27 pages)

Report on the physical, bacteriological and biochemical analyses of seawater samples collected off existing sewage outfalls in the Sierra Leone River Estuary

The studies reported were undertaken as part of a wide environmental feasibility study for the establishment of a modern sewage system in Freetown. The aim of this part of the study was to determine whether the hydrological regime of the Sierra Leone River Estuary would permit the large-scale introduction of sewage into the estuary without damaging the environment. The important factors were whether: 1) there would be sufficient dilution of the sewage; 2) fleatable particles or other substances would create significant adverse effects in the estuarine ecosystem. The outfall sites are described together with the sampling stations, methods and analyses. Results include: 1) T/S profiles; 2) chemical analysis of the water. A review of literature on the Sierra Leone River Estuary is included which provides information on the plankton, benthos and fisheries. Results suggest that at certain points where local circulations occur it would be inadvisable to locate untreated sewage outfalls. Such points are frequently observed in small embayments. These studies have been of short duration but the data can serve as baseline for more extended investigations which would give a more complete picture of the seasonal patterns in the estuary.

Survey of the shrimp stocks of the Sierra Leone inshore shelf : a summary report outlining objectives, observations and recommendations on the status of the Sierra Leone shrimp fishery

This report gives the species and catch-rates per hour of some commercial shrimp species caught in the course of a short survey of inshore shelf fishing grounds. Species seen in significant quantities were: Parapenneopsis atlantica, Parapenaeus longirostris, Penaeus kerathurus and Penaeus duorarum notialis