Iranian Scientific Fisheries Journal
Year:2005 | Volume:13 | Issue:4|Papers Count:18

Seasonal variation and vertical distribution of water temperature, pH, electrical conductivity, dissolved oxygen and chlorophill-a from the Iranian waters of Hormozgan province in the Persian Gulf were studied from Febuary 2001 to Febuary 2002. all parameters were measured by using CID multiparameter probes at 30 sampling stations. Data obtain revealed that seasonal thermocline appears in the survey area during spring, extended in summer, diminishes in autumn and gradualy eliminate during winter season. Variation in electrical conductivity follows the changes in winter temperature through out the year except in winter. Dissolved oxygen was recorded to be higher in the dept layer of 10-25 meters and decreases by increasing depth. Vertical pH of water indicated a decreasing pattern from surface to bottom through out the year, with highest decrease in autumn, when the dissolved oxygen decreases as well. The maximum concentration of chlorophyll-a was recorded at depth layers of 20-40m and 10-20m during first and second half of the year, respectively.

Using length frequency of the Otolithes ruber collected in waters of three southern province of Iran, we estimatd the fish growth parameters and monthly measured fork length of around 1000 fish caught using gill net with a mesh size of 6.5 centimeters in waters of this study area. The length infinity (L∞) in Bushehr, Hormozgan and Sistan and Baluchistan province was estimated as 58.5, 56, 59.5 centimaters, growth coefficient per year (K) as 0.48, 0.43, 0.32 and age at zero length (t◦) as -0.006, -0.002, 0.001 respectively. The relationship between length and weight of the fish in the three provinces determind. The parameters q, band r (correlation coefficient) were 0.173, 2.808, 0.984 for Bushehr, 0.012, 2.962, 0.932 for Hormozgan and 0.050, 2.604, 0.921 for Sistan and Baluchestan province. We also evaluated the average length for the fish caught in different months and landing places. An ANOV A test showed a significant difference (P≤0.05) between the average lengths of the fish caught in different months.

Using length frequency information collected for Parastromateus niger catch in the coastal waters of Sistan and Baluchestan, Oman Sea, we estimated growth parameters of the fish. The data were collected of the fork length of around 887 fish each month during 2001. The length infinity (L∞), growth coefficient (K) and the length at age zero (t0) of the fish measured as 57.8 cm, 0.3 per year and -0.003 respectively. The relationship between the length and weight of the fish was estimated as 0.0469 for "a", 2.829 for "b" and 0.914 for the correlation coefficient. The average length of the fish in different months of the year calculated and a Tukey test showed that this was significantly different.

The fish biodiversity and abundance studied in Boujagh wetland, close to Kiashahr town, south-western Caspian Sea during the year 2002. In each season, samples were collected by using gillnet, common haul seine, cast net and dip net in a 7-15 day sampling period and found one class (Osteichthyes), eight orders, nine families and 25 species and sub-species of the fishes found in the wetland. We showed that of the order Cypriniformes, two families of Cyprinidae with 14 species and sub-species and Cobitidae with two species are living in the wetland. Other fish orders were on]y represented by one family: Esociformes by family Esocidae, Syngnathiformes by Syngnathidae, Cyprinidontiformes by Poecilidae, Siluriformes by Siluridae, Gasterosteiformes by Gasterosteidae, Atheriniformes by Atherinidae and Perciniformes by Gobiidae. Of these orders, Cypriniformes and family Cyprinidae had the most diverse fish species with Blicca bjoerkna being the most abundant.

This sudy was performed to investigating distribution and biomass of two species of brown algae (Colpomenia sinousa and Iyngaria stellata) in costal waters of Hormozgan Province, Southern Iran. We sampled the algae over the years 2001 to 2002 in low tide periods using random 0.5*0.5 quadrats along a transect passing through six sampling stations. The highest distribution extent of the two brown algae species during winter and spring seasons observed which coincided with the highest fluctuation in their biomass. The maximum biomass of C. sinousa in winter and spring was 142 and 75 grams/m2 respectively. For I. stellata, the maximum biomass in the two seasons was 208 and 189 grams/m2 respectively. Analysis of variance showed a significant difference among the biomass of the two algae species over different months and seasons of the year (p<0.05). Hence, we concluded that the species occurrence is seasonal and did not find a significant difference in the biomass of the two species obtained from different sampling stations. However, species appearance in different stations occurred in different months with the western stations showing a 1 to 2 months time Jag compared to that of the eastern stations.

Cutaneous lesions of fish caused by viral, bacterial, parasitic, mechanical and chemical agents are very common normally leadij1g to more infection severity and higher mortality. We studied the healing effects of Phenytoin Sodium on 140 fish specimens. For this reson, the fish samples disinfected by using a saline solution 3% for 14 minutes. An incision 1.5cm long and 2mm deep applied in all fish samples and then the samples divided into four groups of 35 fish specimens. We used the first group as control and treated the other three groups by three doses of Phenytoin Sodium. During the 20 days of the study, water changed as per need and added Phenytoin Sodium at a dose of 2mg/l, 5mg/l and 10mg/l. Over the 20 days of study, healing was recorded in all groups, but groups 2 and 3 showed more healing. The healing initiation was also sooner in groups 2 and 3 compared to other groups. In clinical examination of the healing effects of Phenytoin Sodium, group 3 showed depression, anorexia, increased mucous secretion and ataxia while these symptoms were absent in group 2. We concluded that a solution of 5mg/l of Phenytoin Sodium is the best for improvement of the incision healing in the gold fish.

The fish diversity and distribution investigated in the Mahabad-Chai river of the lake Urmia basin, over the years 1998-1999. Gillnet, beach seine, cast net and electro-shocker used to catch fishes seasonally in 16 stations within 5 regions of the river. We identified 18 species of fish belonging to four families of the bony fishes. The family Cyprinidae with 15 species was the most abundant comprising 98.2 % of the catch, present in all the stations. Families Balitoridae, Siluridae and Poeciliidae were represented only by one species and were the least aboundant, with the Balitoridae being presnt in all the stations. Of the identified fish species, Capoeta capoeta was the most aboundant, Chalcalburnus atropatenae was the second most abundant and Acanthalburnus urmianus was the third most abundant comprising 41.61%, 34.16% and 7.91% of the catch repectively. The least aboundant species were Abramis brama and Gambusia holbrooki with other 13 species coming in between in all regions while other species were present only in some of the regions. Of the identified fish species 11 were native and seven were alien species introduced by Caspian Sea Bony Fishes Research Center. Presence of Pseudorasbora parva and Rhodeus sericeus amarus reported for the first time in the region. Also, among the identified fish, Leuciscus ulanus, Ch. atropatenae and A. urmianus are endemic to Iran, living in the Lake Urmia basin. Having a small stock and narrow distribution in the wild, the Leuciscus ulanus is of especial importance to the fishery managers.

Pick Perch is one of the most valuable fish species of the Caspian Sea, caught commercially each year. During the fishing season of the years 2000-200 I, 18 tons of the fish comprising 11 % of the total commercial catch was caught in the southern Caspian Sea. Of this around 12 tons was caught using beach seine (12 tons) in the coastal waters and another three tons in Anzali Lagoon and the rest is calculated to be the amount of the fish caught without license and recording. The mean fork length, weight and age of the species as 28.11±3.12cm, 253±91.1 grams and 3.09±0.72 years respectively. Also the length-weight relationship calculated as W=0.035*L2.65 (R2=65.66%, N=106). The range of age groups in the catch was 2 - 5 years of which the age groups 2 and 3 comprised 78.5% of the catch. I calculated the Von Bertalanffy growth equation for the fish as: Lt= 52.5 * [1-exp-0.158 * (t+ 1.852)]. The instantaneous rate of total, natural and fishing mortality coefficients were 0.95 yea-1, 0.31 yea-l and 0.64 yea-1 respectively. The calculated exploitation ratio was 0.67. Using the cohort analysis, I estimated the biomass of the species as 31.56 tones. The Gulland's formula used to assess the minimum sustainable yield of the fish as 13.89 tones which is lower than the total catch of the fish. Fishery return coefficient of the fish was measured as 2.87%.

A survey on diatoms diversity and abundance conducted in Iranian waters of the Persian Gulf around Bushehr area in 2004. We used six transects each comprising three sampling stations and sampled diatoms seasonally and found that total diatoms diversity was 97 species and the class Bacillariophyceae was the most diverse and abundant community. The highest diversity in winter with 63 species and the lowest in summer with eight species were observed. We also found the highest abundance of the diatoms in autumn with 627067 cells per cubic meter and the lowest in summer with 345139 cells per cubic meter. Totally, diatoms with an average density of 475336 cells per cubic meter comprised 33.7% of the phytoplankton community. Diatoms had a higher density in lower layers of the water column compared to the middle and upper layers. However, a one-way ANOVA did not show a significant difference in diatoms density in different layers of the water column. Using ANOV, we showed that diatoms density in different seasons were significantly different.

Kilka, a pelagic fish feeding on zooplanktons, are the most abundant fish genus in the Caspian Sea. There are three species of the fish living in the Sea including anchovy (Clupeonella engrauliformes), bigeye (c. grimmi) and common kilka (c. cultriventris). All three species live in the coastal waters of the Sea and comprise part of the commercial catch in the area. The relative frequency of the bigeye ranked second after anchovy over the years 1990-1991 with 6.84% increasing to 12.6% and 21.7% over the years 1997-1998 and decreasing in the subsequent years. We studied biological characteristics of the bigeye kilka over the years 1997-2001 in three fishing regions Amirabad, Babolsar and Anzali. In winter and earlier spring of each year, mature bigeye kilka ready to spawn were always present in the catch. The mean fork length of the fish increased from 95.87mm in 1997 to 105mm in 2000 and decreased to 102.3mm afterwards. Over the same time period, the fork length range became wider with specimens in the upper length classes representing most of the catch. We found that males were always dominant during our study comprising 60 to 90% of the catch. The caught fish consisted of six age classes 1+ .to 6+. During the years 1998 to 1999, the age classes 1+ to 3+ comprised more than 90% of the catch. In the year 2000, we observed a decrease in the age classes 1+ and 2+ and an increase in the age classes 3+ to 5+ compared to that of the pervious years. 10 the year 2001, the age classes 3+ and 4+ decreased and the age classes 5+ and 6+ increased. In recent years, the relative frequency of the bigeye kilka has decreased as a result of the attack by the Mnemiopsis leidyi, but fork length range of the fish has increased and bigger and oder fish are dominant, in the catch.

In this study, excessive growth in submerged aquatic plants such as Coontail (Ceratophyllum demersum) and Pondweed (Potamogeton spp.), floating-leaved species such as Lotus (Nelumbo nucifera) and free-floating species such as Water Fern (Azolla filiculoides) in Anzali Lagoon was observed. We studied effects of excessive growth of these plants on water quality in Anzali Lagoon over the years 1998-2000. Assessed the possible effects of canopy formation and growing sites of these plants on habitat of aquatic animals was studied too. We showed that dissolved oxygen concentration (DO), pH and water temperature are associated with the growth and distribution of the aquatic plants, and established a significant relationship between vertical DO, pH and water temperature and location of canopy of these plants in the water column. Also, an increase in the amount of DO and pH in areas around the canopy and under it for submerged plants observed. This was not the case for floating-leaved and free-floating aquatic plants. The higher water turbulence in areas free from aquatic plants increased DO in lower layers of water column compared to areas covered with aquatic plants. We related the amount of DO and pH of water to growth form in aquatic plants that determines location of canopy formation in these plants. Contrary to the location of canopy and growing site factors, the extent of growth of these plants did not show an affect on DO and pH of water.

The main goal of this study was to understand the reproductive biology of Jinga Shrimp (Metapenaeus affinis) that is found in coastal waters of Hormozgan Province and is relatively unknown to the scientific community. To achieve thia goal, we conducted a monthly sampling over the years 200 I to 2003 sweeping a long area from Bandar Abbass to Sirik in the south of Iran. We found that the sex ratio is not 1:1 either seasonally (except in autumn 2001) or annually (p<0.05). The peak of spawning of the shrimp observed in spring and also calculated the carapace length of female shrimps at first maturity (LM50) as 27.16mm.

After an extensive fish mortality in Sattarkhan Dam, in East-Azarbaidjan provine during the year 2002, we collected 160 specimens of the fish Alburnus filippi and 5 specimens of the fish and Alburnoides biponctatus to exam in the cause of mortality. The samples measured biometrically an examined them for internal and external infections. We found that of the 160 specimens of Alburnus filippi, 131 (81.8%) were infected with Ligula intestinalis and 26 (16.25%) specimens were infected with Bothriocephalus acheillognathi. Of 5 specimens of Alburnoides biponctatus, 4 (80%) were infected with Ligula intestinalis and no Bothriocephalus acheillognathi observed. This is the first report of the Ligula and Bothriocephalus parasites infecting fishes in the Sattarkhan Dam.