Does length-weight equation fit clupeid fishes? An evaluation of LWRs for six clupeids from Iran (Teleostei: Clupeiformes)

This study investigates length–weight relationships of six clupeid species (Alosa braschnikowi, Alosa caspia, Dussumieria acuta, Nematalosa nasus, Sardinella albella and Tenualosa ilisha) captured from three main water bodies of Iran (Persian Gulf, Oman Sea and Caspian Sea), to evaluate if the LWR parameters fit for these fishes having specific morphological characteristics. Based on the obtained results, i) the b value was influenced by recorded length (TL, SL, FL) and body shape, ii) it was within the expected range of 2.27–3.48, iii) length–weight relationships were highly correlated and significant (r2>0.82-0.98, P<0.001), and hence length-weight equations fit well with six clupeid species in the Iranian water bodies. The results presented here, would be useful for fishery biologists and fisheries stake-holders in the study area

Identification and catch composition of fish from set net (Moshta) fishery in Bandar Abbas, Persin Gulf

This study on set-net fishing at the coastal area of Bandar Abbas was conducted from October to April 2012. A totally of 54 set-net operations were recorded, random samplig monthly of 9 set-net from Nakhlenakhoda, Khajehatatta and Suru were conducted. Catch data of every set-net operator were recorded monthly. Fishes were identified, length and weight frequency of fishes were recorded. Results showed that a total of 66 species and 54 genuses belonged to 45 families of fishes were caught by the set-net in Bandar Abbas coastal area. Nakhlnakhoda were consisted of 39 species, 35 genus and 31 families, Khajehatta, 42 species, 40 genus and 37 families and Suru 34 species, 28 genera and 26 families respectively. Analysis of catch composition were showed that in Nakhlnakhoda Goaf (39.7%), Kalar(10.8%) and crabs (9.5%), in Khajehatta Chacunda gizzard shad (38.5%), Mullets (20.9%) and Sardine (5.1%), and in Suru White sardine( 56.4%), Whipfin-silver biddy (7.1%) and Milk fish (6.4%) were dominated. Baed on the data, the frequency of fishes were totally raised in March. Maximum number of fishes were recorded in Nakhlnakhoda (34 species) in October, as well as in Suru (16 species)

Relationship between fish length, otolith length and weigth of Sind sardine Sardinella sindensis, (Day, 1878) from coastal waters of Jask (Oman Sea)

Correlation between fish length, length and weight of otolith of sardine in the Southern waters of Iran still unknown. Therefore, because of commercial and ecological importance of Sardinella sindensis, relationships between fish length (total length), length and weight otolith was studied. In total, 123 Sind sardine were sampled by double –boat purse seiners from coastal waters of Jask from October 2010 to September 2011. Minimum and Maximum of length and weight of fishes were 7.8-19.19 cm and 4.63-59.11 g, respectively. Length and weight of otoliths were 1680.13-3339.45 mm and 0.0005-0.00261 g, respectively. Using t-test, no significantly differences were observed between left and right otolith (P>0.05). The results showed that there was relatively high correlation coefficient between fish length and otolith length (TL= 132.26 OL+ 730.17, r2=0.76), also between fish length and otolith weight (OW=0.00002TL1.6852 ,r2=0.75). For comparison between hypothetical (b) and calculated (b) in this study, t-test carried out, and result showed that the growth of fish and otolith is isometric (P>0.05)

Study of phytoplankton community in coastal waters of Hormozgan province, Qeshm and Leangeh Islands

The study of spatial and temporal variability of distribution of phytoplankton communities in Northern part of the Persian Gulf (Qeshm andLengeh Islands) was studied. In this study, five groups (47 genera) of phytoplankton include Bacillariophyceae, Dinophyceae, Cyanophyceae, Crysophyceae and Euglenophyceae were identified. The results showed that Diatoms group (79.6 %) and Rhizosolenia genus (45.5 %), contributed more towards the percentage composition of different groups and genera of phytoplankton during the study. The annual changes in relative abundance and Margalef, Shannon, pielu and simpson indices were estimated, 0.58-2.56 , 0.08-0.97, 0.23-2.6, 0.09-0.93 respectively. Multivariate analysis of variance showed that during the sudy, density and biological indicators of phytoplankton were significant between seasons (P<0.05). The spatial cluster analysis based on similarity coefficients obtained twoclustersin theareasstudied. The results of the current study suggested that the ​​ecological conditions ofboth Islandsin ranks are instead moderate. Moreover, Phytoplankton of diversity and richness is good

Growth parameters and mortality of Sillago sihama, Forsskål, 1775 (Common silver-biddy) in the Hara Biospher Reserve, Iran

Population parameters of Silver sillago (Sillago sihama) were studied in Hara Biosphere Reserve in Hormozgan province in the south of Iran from September 2016 to August 2017. All specimens were sampled by boat trawl, beach seine, and trapping barriers. Growth parameters were determined using the monthly length-frequency data. The range of total length was between 5.2 to 22.4 cm, and the mean total length was calculated 13.5±0.10 cm for Common silver-biddy. Using length-frequency data analysis, the value of L∞ and K were calculated 30 cm and 0.43 yr-1, respectively. The growth function ø' was calculated as 2.59. Based on growth parameters and monthly length-frequency analysis, four cohorts were distinguished for Common silver-biddy. The rate of natural mortality (M), total mortality (Z), and exploitation rate (E) were estimated at 1.03 yr-1, 2.74 yr-1, and 0.63, respectively. The length-weight relationship was determined as W= 0.0076 L 2.975 (R2=0.9065), indicating algometric growth for Silver sillago. The results showed that the majority of studied fish were juvenile fish. This demonstrates the supporting role of creeks for Sillaginidae as a nursery ground

Study on some population dynamics parameters of Sardinella sindensis (Day, 1878) in Coastal waters of Jask Province

Sind sardine Sardinella sindensis (Day, 1878) is the most important ecological and commercial surface resources in Persian Gulf and Oman sea. This study was carried to study some population dynamics parameters of Sind sardine in Coastal waters of Jask Province during January 2011 to December 2012. A totall 2887 specimens were collected from commercial fishing Purse seiners, monthly. Biometric parameters were measured. The mean length and weight were 14 cm, 29 g respectively and the most dominated length group was 14-15 cm (24.7%). The Von Bertalanffy growth parameters were calculated as L=19.5 (cm), k=1.18 (year-1), t0 = -0.18. Weight- length relationship showed an isometric growth and it was W = aL3.0522 (r2= 0.9432). The natural (M), fishing (F) and total (Z) mortality were 2.19, 0.87 and 3.06 per year respectively. The exploitation rate (E) was 0.29

Assessment of sedimentation rate in sensitive coastal habitats of the Persian Gulf and Sea of Oman (Case study: Lark Island, Qeshm Doha Jetty)

Coastal areas represent the most vulnerable regions of the ocean. Thus, the identification and estimation of sedimentation rates in the sensitive coastal habitats of Qeshm and Lark islands were conducted during 2022-2023. The diving team identified three habitats consisting of natural structures in the north of Larak Island, characterized by the predominance of Acropora sp., and one habitat featuring flora and fauna originating from human-made structures (Doha Qeshm Jetty). These habitats, resembling those on Larak Island but on a smaller scale, were mapped using ArcGIS software 10.1. Three sediment traps were placed at 500-meter intervals in each station to cover each habitat comprehensively. The minimum and maximum sedimentation rates were measured at Larak Islands (St3) with 28 and Doha Qeshm Jetty with 196 (g/m2/day), respectively. Additionally, the minimum and maximum concentrations of suspended substances in the water column, ranging from 9.44 to 21.31 (mg/lit), were observed at these two stations during autumn. The freshness of Acropora sp. served as an indicator in all four habitats, potentially reflecting either the negligible impact of sedimentation rates on communities or the resilience of these communities to sedimentation during the study perio

The morphology of Sagittal otoliths of Psettodes erumei (Bloch and Schneider, 1801) in the north of the Persian Gulf and Oman Sea

This study was conducted to investigate the morphologic and morphometric characteristics of sagittal otolith of Psettodes erumei in the north of the Persian Gulf and Oman Sea (Hormozgan Province). For this purpose, 119 specimens were collected from October 2016 to November 2017. After biometry of the specimens, sagittal otolith pairs were extracted and their morphometric parameters (length, width, perimeter, diameter, area, and weight) were measured and recorded. Then, the otolith size index (OSI), the otolith thickness index (OTI), and the otolith longitude index (OLI) were calculated. The calculated values of OSI (0.05), OTI (0.13), and OLI (2-2.6) showed that sagittal otoliths of P. erumei are large, thin, and have a medium longitude. According to the results, the otolith location side had been identified as a factor affecting the otolith morphometric characteristics. Moreover, the results showed a directional asymmetry between otoliths. Regression models between fish total length and otolith morphometric parameters showed a strong correlation between fish length and otolith length, area, and weight (R2>0.75). The results of this study provide fundamental information for stock identification of P. erumei, a commercially valuable flatfish species, in the north of the Persian Gulf and Oman Sea based on the otolith shape and chemistry analysis and through this provide key information for fishery management and sustainable exploitation of P. erumei in the area