A molecular genetic investigation of the population structure of Atlantic menhaden (Brevoortia tyrannus)

Atlantic menhaden (Brevoortia tyrannus), through landings, support one of the largest commercial fisheries in the United States. Recent consolidation of the once coast-wide reduction fishery to waters within and around Chesapeake Bay has raised concerns over the possibility of the loss of unique genetic variation resulting from concentrated fishing pressure. To address this question, we surveyed variation at the mitochondrial cytochrome c oxidase subunit I (COI) gene region and seven nuclear microsatellite loci to evaluate stock structure of Atlantic menhaden. Samples were collected from up to three cohorts of Atlantic menhaden at four geographic locations along the U.S. Atlantic coast in 2006 and 2007, and from the closely related Gulf menhaden (B. patronus) in the Gulf of Mexico. Genetic divergence between Atlantic menhaden and Gulf menhaden, based on the COI gene region sequences and microsatellite loci, was more characteristic of conspecific populations than separate species. Hierarchical analyses of molecular variance indicated a homogeneous distribution of genetic variation within Atlantic menhaden. No significant variation was found between young-of-the-year menhaden (YOY) collected early and late in the season within Chesapeake Bay, between young-of-the-year and yearling menhaden collected in the Chesapeake Bay during the same year, between YOY and yearling menhaden taken in Chesapeake Bay in successive years, or among combined YOY and yearling Atlantic menhaden collected in both years from the four geographic locations. The genetic connectivity between the regional collections indicates that the concentration of fishing pressure in and around Chesapeake Bay will not result in a significant loss of unique genetic variation.

A note on morphometric and length-weight relationship of Upeneus moluccensis (Bleeker) off Veraval coast

Upeneus moluccensis were collected from the catches of bottom fish trawl of "M. V. Saraswati" off Veraval coast in the area lat. 20 degree 26 N and long. 70 degree 35 E. The fish were analysed for length-weight relationship and morphometric characters. The fishes were found to vary from 116 to 161 mm in length and 20.0 to 50.0 g in weight. The exponent value and correlation coefficient for length-weight relationship was found to be 2.73 and 0.991 respectively.

Length-weight relationship of intertidal molluscs from Mumbai, India

A study on the length-weight relationship of common intertidal molluscs from Mumbai showed a high degree of correlation between their length and weight. Most of the molluscs exhibited isometric growth pattern but in some species, allometric growth was found, which is attributed to maturity, nonlinear growth of shell and the ecological conditions. The variations in the growth rate of Gafriarium divaricatum sampled from two geographically separate sites, Bandstand and NCPA, is a result of variation in ecological conditions.

Additional information on the length-weight relationship of skipjack tuna from the Eastern Tropical Pacific Ocean

ENGLISH: Results of a study of the length-weight relationships of yellowfin (Neothunnus macropterus) and skipjack (Katsuwonus pelamis) tuna from several fishing areas of the Eastern Tropical Pacific Ocean have been published by Chatwin (1959). In that report, a very low exponential value of 2.6261 was obtained for skipjack from Area 14 (off northern Chile, see Chatwin, Figure 1). It was pointed out, however, that this estimate was based on two samples of fish with a very narrow range of total lengths, not representative of the range in the catch, and that it would be desirable to obtain a further estimate based on a larger range of total lengths. In addition, there proved to be significantly large differences among exponents for the areas sampled, precluding use of a single regression equation for all areas. Two important fishing areas remained unsampled (Areas 10 and 13, see Chatwin, Figure 1), and it appeared desirable to collect length-weight measurement data from them, so that estimating equations would be available for all areas. Subsequent to publication of Chatwin's study, samples of skipjack length-weight measurements were obtained from the desired areas. Estimates derived from these data, and their effects on the previous analysis are presented herein. SPANISH:Los resultados de un estudio sobre las relaciones entre la longitud y el peso del atún aleta amarilla (Neothunnus macropterus) y del barrilete (Katsuwonus pelamis) de las diferentes áreas de pesca en el Pacífico Oriental Tropical ya han sido publicados por Chatwin (1959). En ese informe se obtuvo un valor exponencial muy bajo de 2.626 para el barrilete del Area 14 (frente a la costa norte de Chile, ver Chatwin, Figura 1). Se hizo hincapié, sin embargo, en que esta estimación se basaba en dos muestras de peces con una amplitud muy estrecha de longitudes totales, no representativa de la amplitud en la pesca, y que sería deseable obtener una estimación adicional basada en una amplitud mayor de longitudes totales. Además, se comprobó que habian diferencias significativamente grandes entre los exponentes de las áreas muestreadas lo que impedía el usa de una sola ecuación de regresión para todas las áreas. Se quedaron sin muestrear dos importantes áreas de pesca (Areas 10 y 13, ver Chatwin, Figura 1) y pareció deseable recolectar datos de medidas de longitud y peso de estas áreas, de tal manera que hubiesen disponibles ecuaciones estimadoras para todas las áreas. Después de la publicación del estudio de Chatwin, so obtuvieron muestras de medidas de longitud y peso de barriletes de las áreas deseadas. Las estimaciones derivadas de estos datos y sus efectos sabre el análisis previo se dan en el presente informe.

Length-weight relationships of the anchoveta, Cetengraulis mysticetus, in the Gulf of Panama

ENGLISH: Knowledge of the length-frequency distribution and the length-weight relationships of the anchoveta is essential for converting the catch statistics of that species from pounds to numbers of fish. Such conversions are necessary for various types of investigations, especially those involving estimation of the population size and mortality rates. The analysis of the results of a recent tagging program conducted with anchovetas in the Gulf of Panama (Bayliff, 1965) requires that such conversions be made. Length-frequency data for the anchoveta have already been collected and published (Howard and Landa, 1958; Bayliff, 1964). The present report deals with length-weight data from fish collected in various .areas of the Gulf of Panama in all months of the year and in several different years. Opportunity is thus afforded to compare the length-weight relationships of fish of different year classes in different areas, months, and years. SPANISH: El conocimiento de la distribución de la frecuencia de longitud y de las relaciones entre la longitud y el peso de la anchoveta es esencial en las estadísticas de captura de esta especie para la conversión de peso en libras a número de peces. Estas conversiones son necesarias para varios tipos de investigación, especialmente las que se refieren a la estimación del tamaño de la población y de las tasas de mortalidad. Estas conversiones se requieren para analizar los resultados de un programa reciente de marcación de anchovetas en el Golfo de Panamá (Bayliff, 1965). Los datos de la frecuencia de longitud de la anchoveta ya han sido recolectados y publicados (Howard y Landa, 1958; Bayliff, 1964). El presente informe trata de los datos de longitud y peso de los peces recolectados en varias áreas del Golfo de Panamá durante todos los meses del año y durante varios años. Esto ofrece la oportunidad de comparar las relaciones entre la longitud y el peso de peces pertenecientes a varias clases anuales en áreas, meses y años diferentes.

On the methods of determining size/weight characteristics of food organisms of fish. (Determination of the length of Copepoda in larval stages by egg-laying females of the free living freshwater Copepoda). [Translation from: Voprosy Ikhtiologii 14, 182-194, 1960. ]

As is known, copepods play an important role in the nutrition of fish. Therefore with a view to facilitating research on the study of the quantitative side of feeding, there have recently appeared a considerable number of papers devoted to the development of methods for determining the wet. weight of these crustaceans. For the further facilitating of research in the nutrition of fish it would be of great interest to clarify the problem, is there not some kind of rule in the growth of the crustaceans during metamorphosis, and if there is such a rule is it not possible, to determine the length of the larvae at each stage, not by measuring them, but by using the formulae derived on the basis of these rules. This article examines the growth curves of different species of freshwater Copepoda, obtained on the basis of experimental observations in cultures or by way of measurement of mass material at all stages of development in samples from water-bodies. The authors study in particular the ratio of the mean diameter of the eggs to the mean length of the egg-bearing females.

Recolonisation of temporary streams and evolution of a degree of stability of the zoocenose [Translation from: Ecologia Mediterranea No.1 149-164, 1976]

When flow returns to a temporary stream a certain number of plant and animal species establish themselves more or less rapidly on the stream-bed constituting the initial phase of evolution of the re-population. This phase is essentially characterised by the ”awakening” of animal species that passed the dry season in a dormant state and by the development of the first unicellular algae that constitute the periphyton. Then they are succeeded by more or less stable animal groups and the structural complexity increases. The authors of the present study aim to analyse the dynamics of community succession from the return of water to the biotope until its drying up. It is attempted to determine the influence of the duration of flow on this evolution. This work is based on the analysis of population diversity with reference to its two complementary aspects, species richness and equitability. The River Destel which was studied for this project is situated in the Gorge of Ollioules near the town of Toulon.

Length-weight relationship of fishes caught by trawl off Alexandria, Egypt

This paper presents the length-weight relationship parameters (a and b) for 29 fish species, belonging to 16 families, taken by otter trawl fishing from Egyptian Mediterranean waters. The b values obtained ranged from 2.50 to 3.44 (with a mean of 2.926).

Length-weight relationships of commercially important marine fishes and shellfishes of the southern coast of Karnataka, India

The parameters of the length-weight relationship of the form W = aLb are presented for 51 species of commercially important marine fishes and shellfishes caught along the southern coast of Karnataka, India. Samples from commercial (trawl, purse seines, gill nets) and artisanal gears were taken during August 1999 to May 2001. The ‘b’ value ranged between 1.942 and 3.616 with a mean of 2.80, standard deviation of 0.32, and mode of 3.

Length-weight relationships of major carps in Kaptai Lake, Bangladesh

Length-weight relationships and condition factors are presented for Indian major carp Catla catla, Labeo rohita, L. calbasu and Cirrhinus mrigala (Cyprinidae) in a reservoir of Bangladesh (Kaptai Lake).

Length-weight relationship of fishes from Yemen waters (Gulf of Aden and Red Sea)

The data for this study were gathered between 1993 and 1996 on board commercial trawlers from Somalia, China and Yemen and also from the research vessel Ibn Magid belonging to the Marine Science and Resources Research Centre, Aden, Republic of Yemen. Fish were identified using the FAO species identification literature. All fish were measured to the nearest mm (total length) and weighed to the nearest g. Sex was determined by dissection after the length and weight had been measured. The length-weight relationships were calculated using least-squares regression on log-transformed data and the parameters of the relationship of the form of W=aL super(b) are summarized. Maximum and minimum size of fish sampled are also given. Common names and recent changes in nomenclature were taken from ICLARM's FishBase.

Length-weight relationship of fishes caught in the Itaipu Reservoir, Parana, Brazil

Parameters and related statistics of the length-weight relationship of the form W=aL super(b) are presented for 72 species of fish caught in the area of the Itaipu Reservoir in Parana, Brazil. The b values varied between 2.34 and 3.35, with the mean b=2.986 (s.d.=0.230) not significantly different from 3.0 (df=7, p=0.05).

Length-weight relationship of small pelagic fish species of the southeast and South Brazilian Exclusive Economic Zone

The length-weight relationship (LWR) parameters of 23 small pelagic fish species (belonging to 13 families) from the south-southeast Brazilian Exclusive Economic Zone in 1996 and 1997 are presented. The b values varied between 2.72 and 3.53. The samples for this study were collected during hydroacoustic surveys covering an area of 700 000 square km.

Length-weight relationships of demersal fishes from the upper continental slope off Colombia

Parameters of the length–weight relationship of the form W=aLb are presented for 45 demersal fish species caught on the upper continental slope of the Caribbean Sea off Colombia. The b values varied between 2.13 and 4.97, with the mean b = 3.042 (95% CI, 2.887- 3.196).

Length-weight relationships of demersal fishes from the Gulf of Salamanca, Colombia: [part 2]

The parameters a and b of the length-weight relationship of the form W=aL super(b) are presented for 37 fish species, belonging to 17 families, caught during a demersal trawl survey over the period December 1995 to March 1998 in the Gulf of Salamanca, Colombia