Journal of Marine Biology

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Euthynnus affinis with local name: Zardah is an important species in scombrid fishery in the Hormozgan and southern Iran provinces. Catch management of this species in region is requiring to be known some biological parameters such as growth and mortality. In this research according to migration behavior of kawakawa in Hormozgan, Samples were collected from landing at four station: Gavbandy, Kong, Salakh and Jask. During Three years study from 2003 to 2005 more than 25000 specimens were measured, mean ±S.D Values for each year were 64/58±6/27, 64/73±7/2 and 62/96±5/31 respectively. The maximum and minimum total lengths were 25cm and 86cm respectively. Growth and mortality parameters were calculated for the 3 years as below, L∞: 89, 87 and 87 and K: 0.5, 0.52 and 0.53 and t0: -0.30,- 0.46, and -0.48, Z: 1.78, 2.72 and 2.62, M: 0.64, 0.66 and 0.67, F: 1.14, 2.06 and 1.95 respectively. Exploitation ratio (E) was estimated 0.64, 0.75 and 0.74 respectively. Exploitation rate, U : 0.53,0.7,0.68 and Annual total stock at beginning of year: 11566,7881,9060 T and Annual average standing stock , b : 5419, 2678 , 3159 T were also estimated for 2003 – 2005 respectively. Result in this study showed exploitation ratio kawakawa stock is over fishing and decreases exploitation ratio proposed.

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The marine survey for sturgeon stock assessment was conducted to estimate the abundance of each species, total abundance, biomass and their percentage composition. Trawling was carried out in 90 stations that were selected using a random stratified design. In each station trawling carried out up to 30 minute and with 2.5-3 knot speed. In Autumn 2001 totally 127 sturgeon specimens were caught including 90 A. persicus specimens, 34 A. stellatus, 2 A. nudiventrisand 2 Husohuso specimens. The catch composition comprised 70.3% A. persicus, 26.5% A. stellatus, 1.56% A. nudiventrisand 1.56% Husohuso. But in Autumn 2009 totally 62 sturgeon specimens were totally caught including 52 A. persicus specimens, 8 A. stellatus, and 2 A. gueldenstaedtii specimens. The catch composition comprised 83.9% A. persicus, 12.9% A. stellatus, and 3.2% A. gueldenstaedtii.Relative abundance of sturgeons caught in bottom trawls in autumn 2001 was 1.69 specimens per trawl, but in autumn 2009 were 0.69 specimens per trawl. The estimated total abundance of sturgeons in the autumn 2001 survey was 7930 thousand and in survey of autumn 2009 was 3463 thousand specimens. The estimated biomass of sturgeons in the Iranian waters of Caspian Sea in autumn 2001 was 5518.1 tons and in autumn 2009 3014.3 tons .the absolute abundance of commercial sturgeon in autumns 2001and2009were 281330 and 277677 respectively.The biomass of commercial sturgeon sturgeon was estimated 5518.1 tons in autumn2001, while it was 2193.5 tons in autumn 2009.

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Growth parameters, natural mortality and biomass of Cor Venus, Paphiacor were studied in Gassir, Bushehr shoreline areas (from 50˚ 40´ E and 29˚ 14´ N) during September 2008 - 2009. Samples were obtained at bimonthly from Gassir area in a year at low tide. Some transects were selected at random direction and at the zigzag pattern, so that cover all of the shell beds. In each transects one or two sampling quadrat (0.25 m2) was placed random. The length frequency of samples was measured bimonthly, from dextral to sinistral with vernier calipers to the nearest 0.1 millimeter. The length frequency was used to estimate growth and natural mortality parameters. Data analysis was conducted with the most recent version of LFDA statistical software. Stock abundance was estimated in the cold, temperate and hot months of the year.Salinity and water temperature were measured and averaged in the sampling months. Surface sediment samples (0-20 cm depth) were collected from sampling area inhabited by the P. cor.The Von Bertalanffy growth parameters for Paphiacor were estimated as K=0.8Year-1, L¥ = 55 mm and t0 = -0.45. Estimated natural mortality rate for Paphiacor was M = 0.57 and the maximum ages (Tmax) were calculated during 50 months. The mean of abundance of this species was 8.8±2.2 shells per quadrat and with a maximum in February (Bahman) and minimum in November (Abban). The mean of salinity and water temperature was 41.3 psu and 25.2ºC, respectively. More than 88 percent of the bottom sediment in the studied area was included of silt (54.60%) and sands (32.74%).Present results show, two factors, temperature and sediment types affected on the growth and existing of P. cor in the studied area.

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In this study, the stock identification of (Acanthopagrus arabicus) as the dominant species of the genus was carried out by geometric morphometric in the fishing grounds and landing sites of the west and east part of the Hormuz Strait from June 2014 to May 2016.17-point markers (Landmarks) on the left side of the body of A. arabicus were determined and extracted in order to analyzing body shape data. Body shape analysis was showed the most variations on the head and top of the body and significant differences of body shape were proved between west and east of Strait of Hormuz (P<0.05). Landmark positions in the samples of the west Strait of Hormuz were indicated the decrease of body depth, increase of head length, leaning of base, pectoral and ventral fin to upper part of the body, meanwhile it was contrary in the samples of the east. CVA correlation analysis showed a significant difference in body shape in the west and east of the Hormuz Strait (P<0.0001), so the individuals were shown differences and the stocks of this species were separated in the west and east of the Hormuz Strait.

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