scholarly journals Swordfish growth pattern in the strait of Gibraltar; implications for mixing among Atlantic and Mediterranean stocks

2013 ◽  
Vol 15 (1) ◽  
pp. 135 ◽  
Author(s):  
N. ABID ◽  
M. BAKKALI ◽  
G. TSERPES ◽  
M. IDRISSI

A growth study of the swordfish in the Strait of Gibraltar was carried out, based on monthly size frequencies data collected from the Moroccan driftnet fishery during the period 2006-2011. The growth parameters were estimated by the modal progression analysis (MPA), using both the Bhattacharya and NORMSEP methods. The standard von Bertalanffy growth function (VBGF) for length was found to be: Lt =253.6 [1-exp (- 0.17(t + 1.30))]. The growth pattern of swordfish in the Strait of Gibraltar was found to be very similar to that obtained from past studies in various Mediterranean areas. Given the existing growth differences among Atlantic and Mediterranean swordfish, this suggests that the majority of fish caught in this area are most likely belonging to the Mediterranean stock. However, further studies are needed to identify the degree of mixing among stocks.

Crustaceana ◽  
2011 ◽  
Vol 84 (9) ◽  
pp. 1099-1109 ◽  
Author(s):  
M. Arculeo ◽  
S. Lo Brutto ◽  
L. Cannizaro ◽  
S. Vitale

AbstractThe blue and red shrimp Aristeus antennatus (Risso, 1816) is one of the most important fishery resources in the Mediterranean Sea. Monthly samplings of blue and red shrimp from June 2006 to May 2007 were landed by the trawl fleet in two northwest Sicilian fishing harbours (San Vito Lo Capo and Terrasini). The carapace length (CL) frequency distribution of females ranged between 15.00 and 59.00 mm, whereas male CLs ranged between 17.00 and 34.00 mm. The estimated parameters of the Von Bertalanffy growth function (VBGF) for San Vito lo Capo females and males were: CL∞ = 65 mm, K = 0.58 y–1 and CL∞ = 41 mm, K = 0.71 y–1, respectively; while for Terrasini females and males these were: CL∞ = 69 mm, K = 0.65 y–1 and CL∞ = 37 mm, K = 0.8 y–1, respectively. In this study, we update the information on stock structure and growth parameters of the blue and red shrimp in two northwest Sicilian fishing grounds and compare these results with other data recorded in the Mediterranean Basin.


2019 ◽  
Vol 8 (1) ◽  
pp. 85-93
Author(s):  
Maulvi Didit Baskoro ◽  
Edi Wibowo Kushartono ◽  
Irwani Irwani

Lobster pasir (Panulirus homarus) merupakan salah satu jenis lobster yang banyak di temukan di perairan Indonesia. Penelitian ini dilaksanakan pada bulan November 2017 sampai bulan Februari 2018 dengan lokasi pengambilan sampel di Pelabuhan Perikanan Samudra Cilacap (PPSC), di Perairan Cilacap Penelitian ini melihat bagaimana model pertumbuhan, dan status sumberdaya, mulai dari Von Bertalanffy, CPUE dan MSY. Estimasi parameter pertumbuhan lobster pasir (Panulirus homarus) dihitung dengan aplikasi Fisat II. Didapatkan hasil model pertumbuhan lobster pasir ( L∞ = 93.66 cm , K = 0.780 dan t0 -1.0950 mm). Hasil CPUE didapatkan persamaan, nilai linier sebesar  y = -0.0002 + 0.0965 x, nilai R2= 0,09443 untuk data lima tahun ke belakang terhitung dari 2012 sampai 2016 dalam upaya penangkapan (Panulirus sp.). Analisa Maximum sustainable yield (MSY) di lakukan untuk mengetahui besarnya potensi lestari Panulirus sp. dengan registrasi linier y-0.0002x + 0.965. Pendugaan MSY dan upaya penangkapan Foptimum diperoleh dengan 2412 trip dan nilai MSY 1164.031. Produksi Panulirus sp. di tahun 2016 – 2017 di Perairan Cilacap mengalami kenaikan, pada tahun 2016 terjadi kenaikan di bulan Februari, Maret, April dan Desember. Sedangakan pada tahun 2017 terjadi kenaikan di bulan Maret dan Oktober. Kenaikan ini dikarenakan musim lobster berada di bulan Oktober hingga Februari. Perubahan iklim dan penangkapan yang melebihi batas akan berpengaruh terhadap ukuran dan stok Panulirus sp. di alam. The Spiny lobster (Panulirus homarus) is one species of lobster that is widely found in Indonesian. This research was conducted on November 2017 until February 2018 the sample locations at the Cilacap (PPSC), which observed  the growth of models, and the status of resources, regretion Von Bertalanffy Growth function CPUE and MSY. The estimated growth parameters of sand lobster (Panulirus homarus) were  calculated using Fisat II application. The results of the spiny lobster  growth  model were obtained (L∞ = 93.66 cm, K = 0.780 and 0 -1.0950 mm). The CPUE results were obtained equations, linear values of y = -0.0002 + 0.0965 x for five years data from 2012 to 2016 . The Maximum Sustainable Yield (MSY) analysis was carried out to determine the magnitude of the sustainable potential of Panulirus sp. within linear  y-0.0002x + 0.965. The MSY values 1164,031 estimation and (Foptimum) fishing effort were 2.412 trips and MSY values 1164,031. The  production of Panulirus sp. start from  2016 to 2017 in the Cilacap has increased, the fact in 2016 there was an increase on February, March, April and December, while in 2017 there was an increase on March and October. So that the increase due to the lobster season being in October to February.  In addition, climate alteration and capture exceed the effect of  size and stock of Panulirus sp.


2019 ◽  
pp. 23-31 ◽  
Author(s):  
George N. Hotos

Growth and mortality of L. aurata (Risso,1810) were estimated in the lagoon of Klisova-Messolonghi (W. Greece), based on age estimation from scale readings of a total of 1048 individuals, ranging between 10 and 59 cm in total length (TL). Age determination revealed nine age classes (0+ to 8+). Maximum age was found to be 8 years for females and 6 years for males respectively. The growth pattern of L. aurata exhibited allometry (b=3.26). The species seems to achieve 34% of its growth during the first year; thereafter the annual growth rate drops. Both sexes presented similar von Bertalanffy growth curves. The von Bertalanffy growth function for the estimated total length-at-age was found Lt = 70.78 [1 - e -0.129(t+1.345)] for the combined sexes. Otolith weight, length and width were tested and they were found to be very good predictors for age. Between the present L. aurata growth parameters and those of other Mediterranean, Caspian and Atlantic Sea for the same species, there were found significant differences in its growth parameters. The total (Z) and natural (M) mortality rate was found to be 0.54 years-1 and 0.33 years-1 respectively. The estimated exploitation rate was found to be E=0.395 which suggests that the existing fishing pressure on L. aurata is rather moderate in the investigated region.


2007 ◽  
Vol 64 (2) ◽  
pp. 205-218 ◽  
Author(s):  
Jason M Cope ◽  
André E Punt

A way to explicitly incorporate ageing error into the estimation of von Bertalanffy growth function (VBGF) parameters using a random effects (RE) modeling framework is presented. This RE framework also accounts for the effects of selectivity on growth curve estimation by characterizing the distribution of true ages derived from multiple age reads using either an exponential or gamma distribution. Simulation testing across four life histories is used to compare the RE approach with standard nonlinear (SNL) approaches that use the primary, average, or median ages in growth estimation. Sensitivity tests compare the effects of assumed length and ageing error, selectivity, and recruitment variability on the estimation of growth curve parameters. Results support the use of the RE method using a gamma distribution over the SNL methods because RE method estimates of VBGF growth parameters were more precise across life histories and sensitivity trials. This general approach can be applied and expanded to other growth models. Applications demonstrate that the results from RE methods may differ in biologically important ways to those obtained from SNL approaches.


Author(s):  
David K.A. Barnes ◽  
Lloyd S. Peck

Thirty-five specimens of the articulate brachiopod Neorhynchia strebeli were collected from a site at 814 m in the Weddell Sea. This was only the second species of the order Rhynchonellida to be found in Antarctica. Formerly N. strebeli was known solely from abyssal Pacific Ocean localities. A circumantarctic distribution is suggested in addition to the known deep-sea Pacific range. The specimens of this collection showed considerable commissure variation, suggesting that the previously proposed erection of two subspecies on the basis of this character is erroneous, and emphasises the phenotypic plasticity of some articulate brachiopods. The valve lengths and the number of alpha growth rings in the sample showed a normal distribution and a von Bertalanffy growth function was fitted to the data: Lt = 23 (1-exp[-0·228t]). If the alpha growth rings were of annual periodicity, the ages attained by the Antarctic N. strebeli of 11 y would be substantially lower than those reported for other Weddell Sea brachiopods. The epibiotic communities occurring on the valves of N. strebeli were impoverished, which is characteristic of deep water Antarctic brachiopods. The few specimens collected with their substratum were attached to small pebbles, but the typical attachment substrata may be different.


Author(s):  
Ricardo Serrão Santos ◽  
Richard D. M. Nash ◽  
Stephen J. Hawkins

The age and population structure of Parablennius sanguinolentus parvicornis (Valenciennes) (Pisces: Blenniidae) from the Azores have been studied. Total length and weight relationships are given for each sex. Age study was based on otoliths readings. The von Bertalanffy growth function was applied to describe the growth in total length with age. At the end of the first year mean (±SD) total length was significantly different in males (7.1 ±1.5 cm) and females (6.1 ±1.2 cm). One-year-old males participate in reproduction as satellites, whereas females do not. The implications of this in early growth rate of the males is discussed. During the two most important months of the reproductive season (i.e. June and July), the sex ratio was significantly biased towards males, particularly in the larger size classes.


1994 ◽  
Vol 51 (8) ◽  
pp. 1689-1691 ◽  
Author(s):  
William S. Hearn ◽  
George M. Leigh

The properties of polynomial and von Bertalanffy growth functions are compared for analysing data from tag–recapture experiments in which fish are recaptured once. For the quadratic and von Bertalanffy growth functions, explicit formulae are obtained for the expected growth increment in terms of length-at-release, time-at-liberty, and the function parameters. If the least-squares fitting technique is used the von Bertalanffy function fits tag–recapture data with no more bias (probably less) than any other growth function, including polynomial growth functions. A bias-reduction technique for fitting the von Bertalanffy growth function to tag–recapture data is not applicable to other growth functions. We conclude that, apart from the straight line, the von Bertalanffy growth function is the one with the most desirable mathematical and statistical properties for fitting to tag–recapture data. The matter of the function that best characterises the way a specific fish species grows can be adequately addressed only by analyses of multiple measurements of individual fish.


1992 ◽  
Vol 43 (5) ◽  
pp. 1151 ◽  
Author(s):  
S Pauly ◽  
M Soriano-Bartz ◽  
J Moreau ◽  
A Jarre-Teichmann

A modified version of the von Bertalanffy growth function (VBGF) is proposed in which a sine wave modifies a standard version of the VBGF, enabling a smooth transition between rapid summer growth and a variable period of zero growth (in length) during winter or during the dry season for aestivating fishes. The key features of a nonlinear routine for fitting this new model are also presented, with emphasis on the estimation of the period of zero growth. Application examples, to Salmo salar and Trisopterus esmarkii, are presented.


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