Die biologischen Voraussetzungen für einen guten Dorschnachwuchs verbesserten sich 1994 in der westlichen Ostsee

The investigations on the fecundity of cod from different areas of the Baltic Sea started in 1992. The samples were collected in ICES Sub-divisions 25 (Bornholm Sea). 24 (Arkona Sea) and 22 (Mecklenburg and Kiel Bay). This article surnmarizes the results of 435 analysed gonads from females of age groups 1 to 8 with total length of 24 - 116 cm of the years 1992 to 1995. The gonads were prepared and analysed according to the methods which were deseribed in Bleil and Oeberst (1993). The aim of the investigations is to estimate the reproduction potential of cod for different areas and years. For this reason the absolute and relative fecundity were analysed for estimating the dependence on the total length, for age groups and the weight of females. These data were estimated for the populations Gadus morhua morhua and Gadus morhua callarias. Preliminary results have shown that the absolute fecundity (fabs) is dependent on whole weight of the females. The influence of sub-divisions (SD) and years to the fecundity are very low. Additional to this data was calculated the population fecundity for the western Baltic Sea stock (SD 22 and 24). The numbers of produced ripe eggs within the western Baltic were estimated with 4055.59 x 10(9) for 1993 and 6949.85 x 10(9) for 1994.

A-SCALA: an age-structured statistical catch-at-length analysis for assessing tuna stocks in the eastern tropical Pacific Ocean

English: We describe an age-structured statistical catch-at-length analysis (A-SCALA) based on the MULTIFAN-CL model of Fournier et al. (1998). The analysis is applied independently to both the yellowfin and the bigeye tuna populations of the eastern Pacific Ocean (EPO). We model the populations from 1975 to 1999, based on quarterly time steps. Only a single stock for each species is assumed for each analysis, but multiple fisheries that are spatially separate are modeled to allow for spatial differences in catchability and selectivity. The analysis allows for error in the effort-fishing mortality relationship, temporal trends in catchability, temporal variation in recruitment, relationships between the environment and recruitment and between the environment and catchability, and differences in selectivity and catchability among fisheries. The model is fit to total catch data and proportional catch-at-length data conditioned on effort. The A-SCALA method is a statistical approach, and therefore recognizes that the data collected from the fishery do not perfectly represent the population. Also, there is uncertainty in our knowledge about the dynamics of the system and uncertainty about how the observed data relate to the real population. The use of likelihood functions allow us to model the uncertainty in the data collected from the population, and the inclusion of estimable process error allows us to model the uncertainties in the dynamics of the system. The statistical approach allows for the calculation of confidence intervals and the testing of hypotheses. We use a Bayesian version of the maximum likelihood framework that includes distributional constraints on temporal variation in recruitment, the effort-fishing mortality relationship, and catchability. Curvature penalties for selectivity parameters and penalties on extreme fishing mortality rates are also included in the objective function. The mode of the joint posterior distribution is used as an estimate of the model parameters. Confidence intervals are calculated using the normal approximation method. It should be noted that the estimation method includes constraints and priors and therefore the confidence intervals are different from traditionally calculated confidence intervals. Management reference points are calculated, and forward projections are carried out to provide advice for making management decisions for the yellowfin and bigeye populations. Spanish: Describimos un análisis estadístico de captura a talla estructurado por edad, A-SCALA (del inglés age-structured statistical catch-at-length analysis), basado en el modelo MULTIFAN- CL de Fournier et al. (1998). Se aplica el análisis independientemente a las poblaciones de atunes aleta amarilla y patudo del Océano Pacífico oriental (OPO). Modelamos las poblaciones de 1975 a 1999, en pasos trimestrales. Se supone solamente una sola población para cada especie para cada análisis, pero se modelan pesquerías múltiples espacialmente separadas para tomar en cuenta diferencias espaciales en la capturabilidad y selectividad. El análisis toma en cuenta error en la relación esfuerzo-mortalidad por pesca, tendencias temporales en la capturabilidad, variación temporal en el reclutamiento, relaciones entre el medio ambiente y el reclutamiento y entre el medio ambiente y la capturabilidad, y diferencias en selectividad y capturabilidad entre pesquerías. Se ajusta el modelo a datos de captura total y a datos de captura a talla proporcional condicionados sobre esfuerzo. El método A-SCALA es un enfoque estadístico, y reconoce por lo tanto que los datos obtenidos de la pesca no representan la población perfectamente. Además, hay incertidumbre en nuestros conocimientos de la dinámica del sistema e incertidumbre sobre la relación entre los datos observados y la población real. El uso de funciones de verosimilitud nos permite modelar la incertidumbre en los datos obtenidos de la población, y la inclusión de un error de proceso estimable nos permite modelar las incertidumbres en la dinámica del sistema. El enfoque estadístico permite calcular intervalos de confianza y comprobar hipótesis. Usamos una versión bayesiana del marco de verosimilitud máxima que incluye constreñimientos distribucionales sobre la variación temporal en el reclutamiento, la relación esfuerzo-mortalidad por pesca, y la capturabilidad. Se incluyen también en la función objetivo penalidades por curvatura para los parámetros de selectividad y penalidades por tasas extremas de mortalidad por pesca. Se usa la moda de la distribución posterior conjunta como estimación de los parámetros del modelo. Se calculan los intervalos de confianza usando el método de aproximación normal. Cabe destacar que el método de estimación incluye constreñimientos y distribuciones previas y por lo tanto los intervalos de confianza son diferentes de los intervalos de confianza calculados de forma tradicional. Se calculan puntos de referencia para el ordenamiento, y se realizan proyecciones a futuro para asesorar la toma de decisiones para el ordenamiento de las poblaciones de aleta amarilla y patudo.

Diversity of estuarine movements of striped bass (Morone saxatilis): a synoptic examination of an estuarine system in southern New Jersey

We determined the dis-tribution of multiple (n=68; 508−978 mm total length [TL]) striped bass (Morone saxatilis) along the estua-rine salinity gradient in the Mullica River−Great Bay in southern New Jersey over two years to determine the diversity of habitat use and the movements of striped bass. Ultrasoni-cally tagged fish were detected in this estuarine area by means of wireless hydrophones deployed at four gates inside the entrance of the study area and farther up to tidal freshwater (38 km). Numerous individuals frequently departed and returned to the estuary, primarily in the spring and late fall over periods of 15−731 days at liberty. The period of residency and degree of movement of individuals to and from the estuary varied extensively among seasons and years. The diversity of movements in and out of, as well as within, the estuary differed from the less-complex patterns reported in earlier studies, perhaps because of the comprehensive and synoptic nature of this study.

Abundance of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, 1994–2000

Annual abundance estimates of belugas, Delphinapterus leucas, in Cook Inlet were calculated from counts made by aerial observers and aerial video recordings. Whale group-size estimates were corrected for subsurface whales (availability bias) and whales that were at the surface but were missed (detection bias). Logistic regression was used to estimate the probability that entire groups were missed during the systematic surveys, and the results were used to calculate a correction to account for the whales in these missed groups (1.015, CV = 0.03 in 1994–98; 1.021, CV = 0.01 in 1999– 2000). Calculated abundances were 653 (CV = 0.43) in 1994, 491 (CV = 0.44) in 1995, 594 (CV = 0.28) in 1996, 440 (CV = 0.14) in 1997, 347 (CV = 0.29) in 1998, 367 (CV = 0.14) in 1999, and 435 (CV = 0.23, 95% CI=279–679) in 2000. For management purposes the current Nbest = 435 and Nmin = 360. These estimates replace preliminary estimates of 749 for 1994 and 357 for 1999. Monte Carlo simulations indicate a 47% probability that from June 1994 to June 1998 abundance of the Cook Inlet stock of belugas was depleted by 50%. The decline appears to have stopped in 1998.

Gunnislake Fish Counter. Annual Report 1999

This is the Gunnislake Fish Counter, Annual Report 1999 produced by the Environment Agency South West Region on March 2000. The report presents the daily upstream counts of migratory salmonids recorded at Gunnislake Weir fish counting station (SX 435 713) situated on the River Tamar in 1999. The counter data contained within this report covers the period of the commercial migratory salmonid net buy-back scheme and the implementation of the National Spring Salmon Byelaws. The fish counter at Gunnislake is a resistivity based system (Logie 2100A – Aquantic limited) and is installed in the fish pass on the Cornish bank of the River Tamar at the head of the tide. The minimum salmon count for 1999 was 2691. The run pattern observed for salmon and sea trout in 1999 was generally consistent with that of previous years. However, the total combined annual count of salmon and sea trout migrating upstream on the River Tamar in 1999 was 25% higher than the 5 year average (1994 - 1998).

Gunnislake Fish Counter Annual Report 2000

This is the Gunnislake Fish Counter, Annual Report 2000 produced by the Environment Agency South West Region on March 2001. The report presents the daily upstream counts of migratory salmonids recorded on the River Tamar at Gunnislake Weir fish counting station (SX 435 713) situated in 2000. Data contained within this report covers the period of the commercial migratory salmonid net buy-back scheme and the National Spring Salmon Byelaws. The fish counter at Gunnislake is a resistivity based system (Logie 2100A – Aquantic limited) and is installed in the fish pass on the Cornish bank of the River Tamar at the head of the tide. The minimum salmon count for 2000 was 2654. The 2000 upstream count for sea trout was 6417. The run pattern observed for salmon and sea trout in 2000 was generally consistent with that of previous years.

Gunnislake Annual Report 2001

This is the Gunnislake Fish Counter, Annual Report 2001 produced by the Environment Agency South West Region on March 2002. The report presents the daily upstream counts of migratory salmonids recorded on the River Tamar at Gunnislake Weir fish counting station (SX 435 713) situated in 2001. Data contained within this report covers the period of the commercial migratory salmonid net buy-back scheme and the National Spring Salmon Byelaws. The fish counter at Gunnislake is a resistivity based system (Logie 2100A – Aquantic limited) and is installed in the fish pass on the Cornish bank of the River Tamar at the head of the tide. The minimum salmon count for 2001 was 3138. The 2001 upstream count for sea trout was 7503. The run pattern observed for salmon and sea trout in 2001 was generally consistent with that of previous years.

Gunnislake Fish Counter Annual Report 2003

This is the Gunnislake Fish Counter, Annual Report 2003 produced by the Environment Agency South West Region on March 2004. The report presents the daily upstream counts of migratory salmonids recorded at Gunnislake weir fish counting station and trap (River Tamar SX 435 713) in 2003. Data contained within this report covers the period of the commercial migratory salmonid net buy-back scheme and the National Spring Salmon Bylaws. The total combined annual count of upstream migrating salmon and sea trout on the River Tamar in 2003 was 7% higher than the 9-year average. The minimum salmon count for 2003 was 3626. The 2003 upstream count for sea trout was 9913. Trap data for 2003 is consistent with historic trapping and net data in terms of the size split between salmon and sea trout stocks.

National report of the frame survey 2010 on the Uganda side of Lake Victoria

This is a report on the results of the Frame Survey conducted in the Uganda side of Lake Victoria during August 2010 by the LVFO Institutions, namely: the Department of Fisheries Resources (DFR) Uganda and the National Fisheries Resources Research Institute (NaFIRRI) in close collaboration with the District Fisheries offices of Busia, Bugiri, Mayuge, Jinja, Mukono, Kampala, Wakiso, Mpigi, Masaka, Kalangala and Rakai. The authors are grateful to the LVEMP II, for providing funds for the survey and the LVFO secretariat coordination. Fisheries Frame surveys have been carried out on Lake Victoria biannually since 2000 to determine the number of fishers, fish landing sites, and facilities at the landing sites, as well as the composition of fishing crafts, their mode of propulsion, fishing gears and the fish species they target. This information is used to guide development and management of the lake’s fisheries. Following the reorganisation of landing sites into Beach Management Units (BMUs), the number of landing sites decreased from 597 in 2000 to 435 in 2008. The survey in 2010 showed an increase to 503 landing sites, an indication that new landing sites are coming up. The fish landing sites continue to have inadequate facilities such as fish shades, cold rooms to service the fisheries industry and very few (5%) have access to electricity and 32% had access to all weather roads. There has been some progressive improvement in the landing site coverage of basic hygiene and sanitation facilities, especially public toilet facilities from 17% in 2000 to 39% in 2010; and portable water from 4% to 17% respectively. However more effort is required to cover all landing sites. Most landing sites (83%) have access to mobile phone networks which eases communication. 46% of landing sites had access to a Health clinic and 64% had a Primary school within a radius of 2 km.