Investigation of polymorphism by PCR-RFLP method in Cobia fish Rachycentron canadum in the Persian Gulf and Oman Sea

Cobia is a native fish species in Iranian waters in the Persian Gulf and Sea of Oman and has a good internal and foreign market. This fish is a fast growing species and for this reason Iranian Fisheries is considering to go for it culture practices. To go for any utilization such as fishing from wild stocks or culture activities, needs a better understanding of its peculiarities and genetic characteristics of its natural resources. Therefore, this project was discribed and conducted. In this investigation, cuts 2 or 3 cm of fin tissue of  specimen of Cobia obtained from Sistan and Bluchestan, Hormozgan, Bushehr and Khuzestan water provinces, were collected. DNA was extracted by Phenol-chlorophorm method and produced PCR product in length of 1060 and 1450 base pair of two mitochondrial genes COI and NADH2. Using 13 cutting enzymes (4 enzymes were subscriber for both of genes), 205 base pair (from 2510 base pair, equal with %3.8 from gene regains) were directly investigated. But binding patterns of enzymatic digestion of PCR products of both COI and ND genes from electrophoresis were monomorph in all samples and no polymorphism was observed. This may be attributed to the unsuitable choice of COI and ND2 genes for showing of intra specific divergence. But in general non-existence of genetic diversity or noticeable decrease of that among individuals has been reported in regions were fish migration exist and they can freely move between two regions. Therefore, non-observation of polymorphism in the study area might be the case and indicates represents the area. On the other hand, some scientists believe that the distributions of populations in different regions are greatly affected by environmental and physical and ecological factors. Althoug Cobia is a migratory fish, but with regard to the fact that the environmental conditions are different (specially temperature and salinity) between east and west of Persian Gulf and Oman sea, there is a possibility that different genetic groups of this species exist in the regions. Of course It is clear that using more samples and enzymes from other genetically regions could produce better results. Since none of the two investigated genes didn’t show genetic divergence or polymorphism amongst the individuals of one region or between different regions, therefore, statistic analysis for estimating of haplotype diversity or nucleotide diversity and drawing of relationship tree among individuals using available softwares was not possible.

Effect of Aquathol K Treatments on Activity Patterns of Largemouth Bass in Two Coves of Lake Seminole, Georgia

Thirty largemouth bass ( Micropterus salmoide s Lacepde) were implanted with radio tags in late October 2003 in two coves of Lake Seminole, Georgia, and tracked over a 24-hour period about every 10 days to determine their response to herbicide application. After five weeks of tracking, hydrilla ( Hydrilla verticillata Royle) in each cove was treated in early December 2003 with dipotassium salt of endothall (Aquathol K; 7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic acid) at a rate of 3.5 ppm. Largemouth bass were tracked during application and tracking continued for three months post treatment to assess effects of herbicide treatment on activity patterns. The treatment in Desser Cove successfully reduced hydrilla in approximately half the cove. However, the treatment in Peacock Lake completely eliminated all submersed aquatic vegetation (SAV) by April 2004. Movement and activity centers remained similar between treatment periods in Desser Cove, but increased after treatment in Peacock Lake. Depth occupied by telemetered fish decreased after Aquathol K treatment in both coves. In general, behavior of largemouth bass did not change appreciably during treatment, and only minor changes were observed in the posttreatment period in Peacock Lake, where all SAV was eliminated. Fish showed little attraction to or movement away from treatment areas, and fish migration from either cove was nil after treatment. Application of Aquathol K and subsequent reduction of SAV had little effect on largemouth bass behavior or movement. (PDF has 8 pages.)

Demographics by depth: spatially explicit life-history dynamics of a protogynous reef fish

Distribution and demographics of the hogfish (Lachnolaimus maximus) were investigated by using a combined approach of in situ observations and life history analyses. Presence, density, size, age, and size and age at sex change all varied with depth in the eastern Gulf of Mexico. Hogfish (64–774 mm fork length and 0–19 years old) were observed year-round and were most common over complex, natural hard bottom habitat. As depth increased, the presence and density of hogfish decreased, but mean size and age increased. Size at age was smaller nearshore (<30 m). Length and age at sex change of nearshore hogfish were half those of offshore hogfish and were coincident with the minimum legal size limit. Fishing pressure is presumably greater nearshore and presents a confounding source of increased mortality; however, a strong red tide occurred the year before this study began and likely also affected nearshore demographics. Nevertheless, these data indicate ontogenetic migration and escapement of fast-growing fish to offshore habitat, both of which should reduce the likelihood of fishing-induced evolution. Data regarding the hogfish fishery are limited and regionally dependent, which has confounded previous stock assessments; however, the spatially explicit vital rates reported herein can be applied to future monitoring efforts.

Variation in the distribution of walleye pollock (Theragra chalcogramma) with temperature and implications for seasonal migration

Aspects of the feeding migration of walleye pollock (Theragra chalcogramma) in the eastern Bering Sea (EBS) were investigated by examining the relationship between temperatures and densities of fish encountered during acoustic and bottom trawl surveys conducted in spring and summer between 1982 and 2001. Bottom temperature was used as an indicator of spring and summer warming of the EBS. Clusters of survey stations were identified where the density of walleye pollock generally increased or decreased with increasing water temperature. Inferences about the direction and magnitude of the spring and summer feeding migration were made for five length categories of walleye pollock. Generally, feeding migrations appeared to be northward and shoreward, and the magnitude of this migration appeared to increase with walleye pollock size up to 50 cm. Pollock larger then 50 cm showed limited migratory behavior. Pollock may benefit from northward feeding migrations because of the changes in temperature, zooplankton production, and light conditions. Ongoing climate changes may affect pollock distribution and create new challenges for pollock management in the EBS.

Tarpon atlanticus in Colombia: a big fish in trouble

The natural history of Tarpon atlanticus (Valenciennes 1846) is reconstructed based on published information. Tarpon is a remarkable fish because of its peculiar larvae, large adult size, migration patterns and its capability to breathe atmospheric air. Destructive fisheries - some using dynamite - have much reduced the population of tarpon along the Caribbean coast of Colombia, and some catch data are presented which document this.

Length-weight Relationships of Dolphinfish, Coryphaena hippurus, and Wahoo, Acanthocybium solandri: Seasonal Effects of Spawning and Possible Migration in the Central North Pacific

Weight-on-length (W-L) relationships for 2,482 dolphinfish, Coryphaena hippurus, and 1,161 wahoo, Acanthocybium solandri, were examined. Data on fork length, whole (round) weight, and sex were collected for dolphinfish at the Honolulu fish auction from March 1988 through November 1989. Unsexed weight and length data for wahoo were collected at the auction from July 1988 through November 1989. We also used sex specific weight and length data of 171 wahoo collected during 1977–1985 research cruises for analysis. Coefficients of W-L regressions were significantly different between the sexes for dolphinfish. Coefficients did not significantly differ between the sexes for wahoo based on research cruise data. In a general linear model evaluating month as a categorical factor, month was significant for female dolphinfish, male dolphinfish, and wahoo with sexes pooled. W-L and length-on-weight (L-W) relationships were fitted by nonlinear regression for all dolphinfish, female dolphinfish, male dolphinfish, and all wahoo sexes pooled. W-L relationships for monthly samples of female dolphinfish, male dolphinfish, and all wahoo with sexes pooled were also fitted by nonlinear regression. Predicted mean weight at length for wahoo was highest at the beginning of the spawning season in June and lowest after the spawning season in September. Maximum and minimum predicted mean weight at length for both sexes of dolphinfish did not correspond with the peak spawning period (March–May). Plausible migration models in conjunction with reproductive behavior were examined to explain the variability in monthly predicted mean weight at length for dolphinfish.

River Dart Weir and fish pass survey 1992

This is the River Dart, Weir and Fish Pass Survey 1992 report produced by the National Rivers Authority. It goes through the general condition of Weirs and fish passes to determine the extent of problems associated with the upstream and downstream migration of salmonids. It considers solutions where problems exist and investigates the exact use of the resource. It looks at the following Weirs: Totnes, Staverton, Hood, Kilbury, Buckfast, Holne, Mardle (River Mardle), Holybrook (Holybrook), Jordan (West Webburn), Swincombe Intake (River Swincombe), Blackbrook, West Dart, Cowsic (Devonport Leat), Kingfisher Press (Bidwell Brook) and Bagpark (East Webburn). It also contains location maps of the weirs and individual fact sheets along detailed pictures and diagrams.

The effect of abstraction on fish and fisheries

This is the report on the Effect of Abstraction on Fish and Fisheries presented at the 24th IFM Annual Study Course, The Changing Face of Fisheries September 1993 at Cardiff. Water is abstracted from rivers for a wide variety of uses and causing potential for conflicts between abstracters, fisheries and conservation interests, especially during natural low flows. It looks at the potential effects that flow reduction has over various stages of salmonids at various stages of their life history. The flow at the time of smolt migration has been found to be positively correlated with the number of returning adults, and flow is considered to be one of the most important environmental factors inducing salmonids to enter fresh water and ascend rivers. The importance of time series data on fish stocks and angling success together with models which ultimately relate discharge to standing stock are discussed in relation to the setting up of Minimum Acceptable Flows.

The assessment of the flow requirements for upstream migration of salmonids in some rivers of North West England

This is the assessment of the flow requirements for upstream migration of salmonids in some rivers of North West England produced by the North West Water Authority in 1985. This report focuses on the automatic fish counters operating on the resistivity principle used for several years in North West England. This report aims to investigate the flow requirements for upstream migration of salmon and migratory trout. The data obtained confirmed that during summer months most fish movement occurs in the higher range of the available flows, but the migration flow range varied from year to year, depending on prevailing river levels. Of the other environmental variables measured, only water temperature and incident light intensity appear to have any direct association with fish movement. Information on migration flow ranges were used in conjunction with computer simulations of the effects of abstraction proposals on historical flows to assess the implications of these proposals for migratory fish.

Nocturnal migration patterns of two Caribbean reef fishes, Haemulon sciurus and Lutjanus apodus [Poster]

In the Caribbean, many coral reef associated fishes have been observed making diel migrations, yet little is known about the detailed movement pathways and space use patterns of individual fish. Often these migrations occur along temporally or spatially consistent corridors that connect preferred resting and foraging habitats. Recent analysis of gut contents from Haemulids and Lutjanids, has provided evidence that these species forage in seagrass beds and other habitats near their coral reef refuges. Few studies have provided direct and spatially explicit evidence of nocturnal migrations and detailed day and night space use patterns for individual fish. This study integrated manual acoustic telemetry to track two common reef species, the bluestriped grunt (Haemulon sciurus) and schoolmaster snapper (Lutjanus apodus) throughout their daily home range. Space use patterns of these species were then examined using Geographical Information System (GIS) tools to link movement behavior to seascape structure derived in a benthic habitat map. This study represents a novel integration of spatial technologies to enhance our understanding of the movement ecology of adult H. sciurus and L. apodus.

Migration patterns of spiny dogfish (Squalus acanthias) in the North Pacific Ocean

From 1978 to 1988, approximately 71,000 spiny dogfish (Squalus acanthias) were tagged off the west coast of Canada. This program is the most extensive tagging study conducted for a shark species. Twelve years after the last year of tagging, recaptured tagged spiny dogfish are still being reported. As of December 2000, 2940 tagged fish (4.1%) have been recaptured. Spiny dogfish were tagged in three major areas: Strait of Georgia, west coast Vancouver Island, and northern British Columbia waters. Generally, spiny dogfish were recaptured close to their release site; however, extensive migrations (up to 7000 km) did occur. Migration rates varied across release areas. Spiny dogfish tagged in the Strait of Georgia underwent the least extensive movement; only 10–14% of the recaptures occurred outside the strait. Spiny dogfish tagged off the west coast of Vancouver Island or in northern British Columbia waters underwent more extensive movement; approximately 49–80% of the tagged spiny dogfish recaptured outside of the release areas. Spiny dogfish from all three release areas were recaptured off the west coast of United States and Alaska. Most impressive are the recaptures of tagged spiny dogfish off the coast of Japan. Over 30 spiny dog-fish were recaptured near Japan, most of which originated off the west coast of Vancouver Island or from northern British Columbia waters.

Migration patterns of young Pacific bluefin tuna (Thunnus orientalis) determined with archival tags

We investigated the migration and behavior of young Pacific bluefin tuna (Thunnus orientalis) using archival tags that measure environmental variables, record them in memory, and estimate daily geographical locations using measured light levels. Swimming depth, ambient water temperature, and feeding are described in a companion paper. Errors of the tag location estimates that could be checked were –0.54° ±0.75° (mean ±SD) in longitude and –0.12° ±3.06° in latitude. Latitude, estimated automatically by the tag, was problematic, but latitude, estimated by comparing recorded sea-surface temperatures with a map of sea-surface temperature, was satisfactory. We concluded that the archival tag is a reliable tool for estimating location on a scale of about one degree, which is sufficient for a bluefin tuna migration study. After release, tagged fish showed a normal swimming behavioral pattern within one day and normal feeding frequency within one month. In addition, fish with an archival tag maintained weight-at-length similar to that of wild fish; however, their growth rate was less than that of wild fish. Of 166 fish released in the East China Sea with implanted archival tags, 30 were recovered, including one that migrated across the Pacific Ocean. Migration of young Pacific bluefin tuna appears to consist of two phases: a residency phase comprising more than 80% of all days, and a traveling phase. An individual young Pacific bluefin tuna was observed to cover 7600 km in one traveling phase that lasted more than two months (part of this phase was a trans-Pacific migration completed within two months). Many features of behavior in the traveling phase were similar to those in the residency phase; however the temperature difference between viscera and ambient temperature was larger, feeding was slightly more frequent, and dives to deeper water were more frequent.

Water quality studies of the Delaware River with reference to shad migration

For some time pollution of the waters of the Delaware River by municipal and industrial wastes has been suspected of playing a major role in the decline of the shad fishery. Accordingly, studies were planned to ascertain whether any conditions of water quality caused by stream pollution and harmful or lethal to shad were existant in the waters of the Delaware River during the migration periods of the shad.

Use of linear low density polythene film for frozen fish packaging

Physical properties of linear low density polythene film of 60 gauge thickness and its suitability as packaging material in frozen fish industry was studied in comparison with conventional 100 gauge low density polythene film. Both were comparable in water vapor transmission rate both at 38°C and -20°C, overall migration test and :flexibility at low temperatures. ·Even though the tearing strength was inferior to the conventional one, it is of no significance in its use in frozen fish industry. The new film worked out to be more economical than the other one.