Fisheries assessment of Biscayne Bay 1983

Creel and trawl surveys of Biscayne Bay were carried out in 1982-1983 to assess commercial fish and macro-invertebrate habitats and fisheries. Dredged and/or barren bottom was dramatically less productive than seagrass, algae or hard bottom areas. Low fish abundance and diversity in north Biscayne Bay appeared to be correlated with high turbidity and low seagrass abundance. Substantive increases in fish and crustacean productivity in north Biscayne Bay will occur only if seagrass communities can be re-established. Deeper dredged areas in North Bay will not likely become recolonized with seagrass even if turbidity levels are reduced. Hard bottom areas in South Bay are associated with high diversity of fish fauna and serve as nursery areas for several highly desirable species (e.g. hogfish, yellowtail snapper, lane snapper). The area between Julia Tuttle and 79th Street Causeways, which had very dense seagrass abundance, was the richest area on either North or South Biscayne Bay for juvenile fish and shrimp. This basin can serve as a model for the potential of the remainder of North Bay.

Deepwater Horizon oil spill: assessment of potential impacts on the deep soft-bottom benthos; interim data summary report

A study was initiated in May 2011, under the direction of the Deepwater Horizon (DWH) Natural Resource Damage Assessment (NRDA) Deepwater Benthic Communities Technical Working Group (NRDA Deep Benthic TWG), to assess potential impacts of the DWH oil spill on sediments and resident benthic fauna in deepwater (> 200 meters) areas of the Gulf. Key objectives of the study were to complete the analysis of samples from 65 priority stations sampled in September-October 2010 on two DWH Response cruises (Gyre and Ocean Veritas) and from 38 long-term monitoring sites (including a subset of 35 of the original 65) sampled on a follow-up NRDA cruise in May-June 2011. The present progress report provides a brief summary of results from the initial processing of samples from fall 2010 priority sites (plus three additional historical sites). Data on key macrofaunal, meiofaunal, and abiotic environmental variables are presented for each of these samples and additional maps are included to depict spatial patterns in these variables throughout the study region. The near-field zone within about 3 km of the wellhead, where many of the stations showed evidence of impaired benthic condition (e.g. low taxa richness, high nematode/harpacticoid-copepod ratios), also is an area that contained some of the highest concentrations of total petroleum hydrocarbons (TPH), total polycyclic aromatic hydrocarbons (total PAHs), and barium in sediments (as possible indicators of DWH discharges). There were similar co-occurrences at other sites outside this zone, especially to the southwest of the wellhead out to about 15 km. However, there also were exceptions to this pattern, for example at several farther-field sites in deeper-slope and canyon locations where there was low benthic species richness but no evidence of exposure to DWH discharges. Such cases are consistent with historical patterns of benthic distributions in relation to natural controlling factors such as depth, position within canyons, and availability of organic matter derived from surface-water primary production.

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.

Swimming depth, ambient water temperature preference, and feeding frequency 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. The archival tag measures environmental variables, records them in its memory, and estimates daily geographical locations based on measured light levels. Of 166 archival tags implanted in Pacific bluefin tuna that were released at the northeastern end of the East China Sea from 1995 to 1997, 30 tags were recovered, including one from a fish that migrated across the Pacific. This article describes swimming depth, ambient water temperature, and feeding frequency of young Pacific bluefin tuna based on retrieved data. Tag performance, effect of the tag on the fish, and horizontal movements of the species are described in another paper. Young Pacific bluefin tuna swim mainly in the mixed layer, usually near the sea surface, and swim in deeper water in daytime than at nighttime. They also exhibit a pattern of depth changes, corresponding to sunrise and sunset, apparently to avoid a specific low light level. The archival tags recorded temperature changes in viscera that appear to be caused by feeding, and those changes indicate that young Pacific bluefin tuna commonly feed at dawn and in the daytime, but rarely at dusk or at night. Water temperature restricts their distribution, as indicated by changes in their vertical distribution with the seasonal change in depth of the thermocline and by the fact that their horizontal distribution is in most cases confined to water in the temperature range of 14−20°C.

Age, growth, and mortality of the Mayan cichlid (Cichlasoma urophthalmus) from the southeastern Everglades

Mayan cichlids (Cichlasoma urophthalmus) were collected monthly from March 1996 to October 1997 with hook-and-line gear at Taylor River, Florida, an area within the Crocodile Sanctuary of Everglades National Park, where human activities such as fishing are prohibited. Fish were aged by examining thin-sectioned otoliths, and past size-at-age information was generated by using back-calculation techniques. Marginal increment analysis showed that opaque growth zones were annuli deposited between January and May. The size of age-1 fish was estimated to be 33–66 mm standard length (mean=45.5 mm) and was supported by monthly length-frequency data of young-of-year fish collected with drop traps over a seven-year period. Mayan cichlids up to seven years old were observed. Male cichlids grew slower but achieved a larger size than females. Growth was asymptotic and was modeled by the von Bertalanffy growth equation Lt=263.6(1–exp[–0.166(t–0.001)]) for males (r2=0.82, n=581) and Lt=215.6 (1–exp[–0.197(t–0.058)]) for females (r2= 0.77, n=639). Separate estimates of total annual mortality were relatively consistent (0.44–0.60) and indicated moderate mortality at higher age classes, even in the absence of fishing mortality. Our data indicated that Mayan cichlids grow slower and live longer in Florida than previously reported from native Mexican habitats. Because the growth of Mayan cichlids in Florida periodically slowed and thus produced visible annuli, it may be possible to age introduced populations of other subtropical and tropical cichlids in a similar way.

Effect of thermal pollution on the hydrological parameters of River Jhelum (J & K)

The Buniyar hydroelectric project and the lower Jhelum Barrier at Gantamulla constructed across river Jhelum are in operation from several years. The two power stations have changed the hydrological features of the area where dam is situated. Therefore, the impact of hydroelectric projects on fishery resources of river Jhelum is a matter of great concern. The treated water from the power house is released through turbines, having cooling effect on them. The change in the hydrological parameters such as increase in temperature, depletion of oxygen etc. might have brought fishes under stress which is the main cause in decreased population of finfishes from site to site. The golden mahseer, Tor putitora which was once an abundant species in river Jhelum has disappeared due to human intervention. The prevailing water quality around hydroelectric projects is unsuitable for finfishes of river Jhelum.

Preservation of cotton fish net twines by tanning 1. Optimum concentration of tanning

Samples of tannin-containing preservatives used by fishermen in India for treating cotton nets were collected and qualitative and quantitative characterisation of the tannins made. The concentrations of different tannins required to impart optimum periods of preservation to the net were worked out and found to be 2% in 8 out of 10 materials studied.

Technological aspects of preservation and processing of edible shell fishes IV. Comparative efficiency of different glazes in the preservation of frozen crab meat

The present work was undertaken to enlighten upon the comparative efficiency of different glazes in improving the quality of frozen crab meat (Scylla Serrata).

Occurrence of enterotoxigenic staphylococci in frozen fishery products

Sixty six samples of frozen fishery products consisting of frozen crab meat, frozen prawns, frozen cuttlefish and frozen mussel collected from nine cold stores situated in and around Cochin city were examined for coagulase positive staphylococci. Forty eight samples (72.72%) revealed the presence of coagulase positive staphylococci, which were then tested for enterotoxigenity, employing cellophane-over-agar method for toxin production and optimum-sensitivity-plate (OSP) method for toxin detection. Seventy seven out of one hundred and two (75.49%) coagulase positive staphylococcal isolates from the above products produced enterotoxins A, B, C, D and E either singly or in combinations. Enterotoxin A and D were detected more often than others. The occurrence of enterotoxigenic staphylococci in frozen fishery product is reported for the first time in this country.

On the development of a mercury-free ternary aluminium anode for cathodic protection

The development of a new mercury-free ternary aluminum anode (CIFTAL) for cathodic protection of marine structures is described. The new anode demonstrated a current efficiency of 83.5% to 85.4% in a current density range of 5.6 to 166.7 mAdmˉ². The current efficiency remained practically stable at 1.4 mAdmˉ² over a test period of 300 days. The service trials of the anode on steel trawlers and aluminum (Indal M 57 S) sheathed wooden boats have shown satisfactory performance in terms of uniform dissolution, current efficiency and driving voltage. In the wake of legislations restricting the use of anodes containing mercury in an endeavor to control the mercury pollution of the near shore aquatic environment, the new anode (CIFTAL) with its stable current output and high current efficiency merits significance in marine cathodic protection.

Study of physicochemical, microbial and sensory properties of surimi produced from black mouth croaker (Atrobucca nibe) at freezing condition (-18ºC)

Black mouth croaker (Atrobucca nibe) is considered as a new valuable fish stock in the Oman Sea. In this study, surimi was manufactured from nonmarket size of the fish, manually and different cryoprotectant agents were added to the surimi. Finally changes in physiochemical, microbiological and sensory quality, characteristics of the surimi and kamaboko gel samples were assessed during 6 months at freezing storage (-18ºC). Surimi samples with the addition of Iranian tragacanth gum (TG), xanthan gum (XG), chitosan (CS) and whey protein concentrate (WPC) at 1% (w/w) were prepared to evaluate their impacts as a cryoprotectant on the surimi, individually. The results showed that the whiteness and lightness indexes in all surimi samples were gradually decreased during frozen storage. This trend of decreasing was more intensity in the control sample from 61.08±0.131 to 54.21±0.067 was recorded (p<0.05). Water holding capacity (WHC) in all treatments was decreased during 6 months. The lowest WHC (g/g) was obtained in the surimi without cryoprotectants and maximum WHC was measured in Tcs and Twpc samples, respectively (p<0.05). The lowest breaking force was calculated in Txg (166.00±22.627 g) and Tc (271.50±263.16 g) during 6 months at frozen storage, respectively (p<0.05), while Twpc treatment with slight variations showed the highest breaking force (p<0.05). Also, the lowest gel strength was obtained in Txg (68.22±6.740 g.cm) after 6 month of frozen storage (p<0.05). All Kamaboko surimi gels texture profile analysis parameters decreaced with increasing shelf life. This decreasing trend in the control sample was more severe. Floding results were reduced in all samples during storage (p<0.05). The best protective results probably were obtained in WPC, chitosan and commercial cryoprotectant agents, respectively due to protein stabilization of myofibrillar proteins and the protein-protein network structure, leading to the formation of surimi gel with strong textural properties during frozen conditions. The average number of surimi polygonal structures were significantly decreased (number per mm2) and their area were significantly increased (μm2) in all treatments (p<0.05). With increasing storage time, moisture, protein contents and pH were decreaced. Maximun TVB-N index was calculated in Tc (7.93±0.400 mg/100g) and Txg (7.88±0.477), respectively (p<0.05). TBRAs index was increased in all treatments during frozen storage, while this trend was reached in maximum value in Tc (p<0.05). Sensory evaluation of the fish finger quality characteristics (color, odor, texture and overall acceptability) preapare from frozen black mouth croaker surimi was decreaced during 6 month frozen storage. After the period of frozen storage the highest quality scores were measured in Twpc, Tcs and Tcc samples, respectively (p<0.05). In this study, coliform bacteria were not found in all treatments during frozen storage. The surimi sample containing chitosan showed lower mesophilic and psychrotropic bacteria (log cfu/g) than other treatments during frozen storage (p<0.05). Salt-soluble proteins extractions of all treatments were decreased during frozen storage. This decreacing trend was highest in Tcs (45.74±0.176%) and lowest in Tc treatments after 6 month of frozen storage (29.92±0.224%) (p<0.05). Although commercial cryoprotectant agents were successful in limiting the denaturation of proteins but sugar contents were not accepted for diabetics or those who disagree with the sweet taste and high calorie food. Hence, commercial cryoprotectant agents can be replaced with whey protein concentrate and chitosan at 1% level (w/w) consider that they were showed proper protection of the surimi myofibrillar proteins during storage.

Studies on distribution, diversity and production of macrobenthic fauna in the Chahbahar Bay

The population density, distribution, diversity and secondry production of macrobenthic fauna of the inner Chahbahar Bay were studied through bi-monthly sampling from April 1995 to March 1996. Samples were collected from water near the bottom and sediment at 14 stations inside the Bay and one reference station located outside at the entrance to the Bay. The environmental parameters Such as temperature, water depth, salinity, pH and dissolved oxygen as well as percentage silt-clay and total organic matter of the sediment were measured. The faunal population density and their distribution is discussed in relation to the environmental changes. results obtained indicated both spatial and temporal heterogeneity in faunal distribution of the Chahbahar Bay. The total of 18 groups of macrofauna were identified in all samples. Amphipods formed the dominant group (21%) followed by polychaetes (19%), gastropods (15.7%) bivalves (10.6%) and all other groups (33.7%). Seasonal changes in faunal density is shown in relation to Indian Ocean southwest monsoon,the result of which indicated lower population density during monsoon (June to September) than that of the premonsoon (February to May) and post monsoon (October to January) periods. The numerical abundance of macrobenthos varied from 10260.m2 before monsoon to 5190 m2 during monsoon season. Three dominant groups of macrofauna including polychaetes, gastropods, and bivalves were identified in all collected samples. Indices of diversity, richness and evenness were calculated for these three dominant groups. The Shannon-Weaver information index was used to describe the spatially and temporally variation in diversity of these three major faunal groups. The results exhibited lower faunal diversity during monsoon period. The annual production of two dominant macrofauna species including a species of bivalve, Nuculana acuta and a species of Cephalochordata, Branchiostoma lanceolatum were measured by using age group determination. Furthermore the mean biomass and total annual production of macrobenthic fauna were estimated for the whole studied area. The potential yield of demersal fishery resources (fish and crustacean) then estimated and worked out to be 15360 tons/year asuming 10% ecological efficiency of hypothetical pyramid from 3rd to 4th marine trophic level. Accordingly the annual exploitable demersal fishery resources for the entire Chahbahar Bay was estimated to be 7600 to 8500 tons/year by taking 50 to 55% of the total estimated potential in to account.

Nutritive value of fish of Lake Tanganyika [part] I: Amino acid composition

The amino acid composition was determined of three economic important fish species of Lake Tanganyika, representing 95% of the tolal catch:Stolothrissa tanganicae Regan, Limnothrissa miodon Boulenger and Luciolates stapersii Boulenger. The analysis of the whole sun dried fish indicate that, compared with Tilapia macrochir, beef and the whole hen's egg, the fish is of a very high nutritive value. The free amino acids in the dried fish count for an average of 11 %, indicating the degree of auteolysis.