Variability in supply and cross-shelf transport of pink shrimp (Farfantepenaeus duorarum) postlarvae into western Florida Bay

The variability in the supply of pink shrimp (Farfantepenaeus duorarum) postlarvae and the transport mechanisms of planktonic stages were investigated with field data and simulations of transport. Postlarvae entering the nursery grounds of Florida Bay were collected for three consecutive years at channels that connect the Bay with the Gulf of Mexico, and in channels of the Middle Florida Keys that connect the southeastern margin of the Bay with the Atlantic Ocean. The influx of postlarvae in the Middle Florida Keys was low in magnitude and varied seasonally and among years. In contrast, the greater postlarval influx occurred at the northwestern border of the Bay, where there was a strong seasonal pattern with peaks in influx from July through September each year. Planktonic stages need to travel up to 150 km eastward between spawning grounds (northeast of Dry Tortugas) and nursery grounds (western Florida Bay) in about 30 days, the estimated time of planktonic development for this species. A Lagrangian trajectory model was developed to estimate the drift of planktonic stages across the SW Florida shelf. The model simulated the maximal distance traveled by planktonic stages under various assumptions of behavior. Simulation results indicated that larvae traveling with the instantaneous current and exhibiting a diel behavior travel up to 65 km and 75% of the larvae travel only 30 km. However, the eastward distance traveled increased substantially when a larval response to tides was added to the behavioral variable (distance increased to 200 km and 85% of larvae traveled 150 km). The question is, when during larval development, and where on the shallow SW Florida shelf, does the tidal response become incorporated into the behavior of pink shrimp.

Surveying bacterial human pathogens in shrimp culture in Thailand

Any presence of bacterial human pathogen in shrimp products may be of public health concern. This note concludes that Salmonella do not appear to constitute a part of the microbial flora where shrimp culture is practiced in Thailand. Vibrio cholerae 01, the cause of cholera are rarely recovered from the environment with no isolates containing genes encoding cholera toxin. Further studies are needed to describe the prevalence of bacterial human pathogens in shrimp culture, especially determination of possible postharvest cross-contamnation with these pathogens

The marine fisheries of Trinidad and Tobago

The marine fisheries of Trinidad and Tobago are mainly artisanal and involve about 8,000 fishers. The main fishing gear used are the gillnets, the troll, the shrimp trawl, the fishpot and the industrial longline. Landings total approximately 14,000 t annually with Scomberomorus brasiliensis, shrimps and sharks being the most abundant in the landings. Assessment studies indicate overfishing and inferior marketing is an important issue. Underexploited resources include clupeiods, deep shell and slope resources, and lobsters. The shrimp trawl and longline by-catch are not fully utilized. Fishery legislation is mostly uotdated and a fisheries policy, including new legislation, is being developed to help solve the problems and effectively manage the fisheries.

Catching and rearing postlarval cleaner shrimp for the aquarium trade: results from a WorldFish Center project in Solomon Islands

Between 1999 and 2003, the WorldFish Center in Solomon Islands conducted research into the feasibility of a new fishery based on the capture and culture of postlarval coral reef fish for the live fish trade. The work was carried out in two phases: a research phase from late 1999 to the end of 2002; and a “finetuning” phase in 2003. Most of the species were of value to the marine aquarium trade, with very few live reef food fish recorded. The most valuable ornamentals were the banded cleaner shrimp, Stenopus species. Cleaner shrimp were harvested using crest nets, the method being modified with the addition of a solid, water-retaining cod-end designed to increase survival at capture. Grow-out techniques were improved by rearing the shrimp separately in jars to prevent aggression. The jars were painted black to protect the shrimp from sunlight. An economic model using experimental catch data and farm gate prices indicates that the fishery based on shrimp, supplemented with small numbers of lobster and fish is economically viable. The next step will be setting up a demonstration farm in a village in the Western Province of Solomon Islands.

Molecular probes and polymerase chain reaction (PCR) -based kits for diagnosis of shrimp diseases

Technology for effective and fast diagnosis of animal diseases is essential for developing aquaculture management strategies. This paper reviews the conventional techniques for shrimp disease diagnosis and discusses the emergence of nuclei acid probes and polymerase chain reaction (PCR)-based kits as powerful tools for rapid and accurate detection of shrimp diseases.

Escalation in shrimp production in the Sierra Leone industrial fishery

Applying Turkey's jackknife method on MSY estimates from the surplus production models of Schaefer and Fox showed that the optimum yield for shrimps in industrial fishery in Sierra Leone is estimated at 2,686.8 t with 15,822 fishing days. Annual catch for 1996 was 2,788 t, indicating an escalation in exploitation which, if prolonged, could bring reduced productivity as experienced in the fishery some years ago.

Culture of prawn in rotation with shrimp

A progressive farmer in Tamil Nadu state, India experimented with crop rotation and successfully cultured Penaeus monodon during the dry season and Macrobrachium rosenbergii during the wet season. The details of M. rosenbergii culture are discussed in this article. Rotation with M. rosenbergii did help the farmer overcome the disease problem since farmers who exclusively cultured P. monodon in the nearby areas during the same season suffered losses due to white spot disease.

Improvement of traditional shrimp culture in the Mekong Delta

Improvements to traditional brackishwater shrimp culture in the Mekong Delta, Vietnam are discussed. A technical support program has been implemented based on a so-called improved extensive shrimp culture method, as previously developed and tested by the Artermia and Shrimp Research and Development Center (ASRDC). The program focuses on: 1) the use of hatchery-produced postlarvae (of Penaeus monodon and P. merguinensis) nursed for three to four weeks, and 2) the application of low-cost pond management practices including predator control, supplementary feeding and frequent water renewal. A credit program, managed as a revolving fund was made available. A dialogue among participating farmers was encouraged through the organization of group meetings before and after each production cycle.

Expansion of improved-extensive shrimp culture in the Mekong Delta

This paper describes the expansion of improved-extensive shrimp (Penaeus monodon) farming in the Mekong Delta, southern Vietnam, emphasizing management decisions, technological constraints and economics.

Use of enriched live prey in promoting growth and maturation of tiger shrimp (Penaeus monodon)

This study was undertaken to determine the effect of nutritional management of broodstock of Penaeus monodon on growth and maturation. Test specimens were obtained from a grow-out pond before attainment of maturity and were reared in hatchery tanks. Four types of dietary treatments (M1–M4) were given to separate batches that were run in duplicate. Feeding trials continued for five months. A diet with live bloodworm, bioencapsulated to contain tricalcic phosphate as its major component, was found to be the most efficient. Specimens of this particular batch assimilated food more efficiently, grew at a faster rate and attained maturity earlier than other groups. Bloodworm provided the lipid fractions for which there is no de novo synthesis in shrimp. The enrichment product acted by promoting somatic growth and increasing transfer of biochemical constituents needed by the ovary for develop

The U.S. Gulf of Mexico Pink Shrimp, Farfantepenaeus duorarum, Fishery: 50 Years of Commercial Catch Statistics

U.S. Gulf of Mexico, pink shrimp, Farfantepenaeus duorarum, catch statistics have been collected by NOAA’s National Marine Fisheries Service, or its predecessor agency, for over 50 years. Recent events, including hurricanes and oil spills within the ecosystem of the fishery, have shown that documentation of these catch data is of primary importance. Fishing effort for this stock has fluctuated over the 50-year period analyzed, ranging from 3,376 to 31,900 days fished, with the most recent years on record, 2008 and 2009, exhibiting declines up to 90% relative to the high levels recorded in the mid 1990’s. Our quantification of F. duorarum landings and catch rates (CPUE) indicates catch have been below the long-term average of about 12 million lb for all of the last 10 years on record. In contrast to catch and effort, catch rates have increased in recent years, with record CPUE levels measured in 2008 and 2009, of 1,340 and 1,144 lb per day fished, respectively. Our regression results revealed catch was dependent upon fishing effort (F=98.48df=1, 48, p<0.001, r2=0.67), (Catch=1,623,378 + (520) × (effort)). High CPUE’s measured indicate stocks were not in decline prior to 2009, despite the decline in catch. The decrease in catch is attributed in large part to low effort levels caused by economical and not biological or habitat related conditions. Future stock assessments using these baseline data will provide further insights and management advice concerning the Gulf of Mexic

Simulation of Tail Weight Distributions in Biological Year 1986–2006 Landings of Brown Shrimp, Farfantepenaeus aztecus, from the Northern Gulf of Mexico Fishery

Size distribution within re- ported landings is an important aspect of northern Gulf of Mexico penaeid shrimp stock assessments. It reflects shrimp population characteristics such as numerical abundance of various sizes, age structure, and vital rates (e.g. recruitment, growth, and mortality), as well as effects of fishing, fishing power, fishing practices, sampling, size-grading, etc. The usual measure of shrimp size in archived landings data is count (C) the number of shrimp tails (abdomen or edible portion) per pound (0.4536 kg). Shrimp are marketed and landings reported in pounds within tail count categories. Statistically, these count categories are count class intervals or bins with upper and lower limits expressed in C. Count categories vary in width, overlap, and frequency of occurrence within the landings. The upper and lower limits of most count class intervals can be transformed to lower and upper limits (respectively) of class intervals expressed in pounds per shrimp tail, w, the reciprocal of C (i.e. w = 1/C). Age based stock assessments have relied on various algorithms to estimate numbers of shrimp from pounds landed within count categories. These algorithms required un- derlying explicit or implicit assumptions about the distribution of C or w. However, no attempts were made to assess the actual distribution of C or w. Therefore, validity of the algorithms and assumptions could not be determined. When different algorithms were applied to landings within the same size categories, they produced different estimates of numbers of shrimp. This paper demonstrates a method of simulating the distribution of w in reported biological year landings of shrimp. We used, as examples, landings of brown shrimp, Farfantepenaeus aztecus, from the northern Gulf of Mexico fishery in biological years 1986–2006. Brown shrimp biological year, Ti, is defined as beginning on 1 May of the same calendar year as Ti and ending on 30 April of the next calendar year, where subscript i is the place marker for biological year. Biological year landings encompass most if not all of the brown shrimp life cycle and life span. Simulated distributions of w reflect all factors influencing sizes of brown shrimp in the landings within a given biological year. Our method does not require a priori assumptions about the parent distributions of w or C, and it takes into account the variability in width, overlap, and frequency of occurrence of count categories within the landings. Simulated biological year distributions of w can be transformed to equivalent distributions of C. Our method may be useful in future testing of previously applied algorithms and development of new estimators based on statistical estimation theory and the underlying distribution of w or C. We also examine some applications of biological year distributions of w, and additional variables derived from them.

Size-composition of Annual Landings in the White Shrimp, Litopenaeus setiferus, Fishery of the Northern Gulf of Mexico, 1960–2006: Its Trend and Relationships with Other Fishery-dependent Variable

The potential for growth overfishing in the white shrimp, Litopenaeus setiferus, fishery of the northern Gulf of Mexico appears to have been of limited concern to Federal or state shrimp management entities, following the cataclysmic drop in white shrimp abundance in the 1940’s. As expected from surplus production theory, a decrease in size of shrimp in the annual landings accompanies increasing fishing effort, and can eventually reduce the value of the landings. Growth overfishing can exacerbate such decline in value of the annual landings. We characterize trends in size-composition of annual landings and other annual fishery-dependent variables in this fishery to determine relationships between selected pairs of these variables and to determine whether growth overfishing occurred during 1960–2006. Signs of growth overfishing were equivocal. For example, as nominal fishing effort increased, the initially upward, decelerating trend in annual yield approached a local maximum in the 1980’s. However, an accelerating upward trend in yield followed as effort continued to increase. Yield then reached its highest point in the time series in 2006, as nominal fishing effort declined due to exogenous factors outside the control of shrimp fishery managers. The quadratic relationship between annual yield and nominal fishing effort exhibited a local maximum of 5.24(107) pounds (≈ MSY) at a nominal fishing effort level of 1.38(105) days fished. However, annual yield showed a continuous increase with decrease in size of shrimp in the landings. Annual inflation-adjusted ex-vessel value of the landings peaked in 1989, preceded by a peak in annual inflation-adjusted ex-vessel value per pound (i.e. price) in 1983. Changes in size composition of shrimp landings and their economic effects should be included among guidelines for future management of this white shrimp

Review of the California Trawl Fishery for Pacific Ocean Shrimp, Pandalus jordani, from 1992 to 2007

The commercial bottom trawl fishery for Pacific ocean shrimp, Pandalus jordani, or pink shrimp, operates mostly off the west coast of the contiguous United States. The California portion of the fishery has not been thoroughly documented or reviewed since the 1991 fishing season, despite its fluctuating more during the last 16 years (1992–2007) than at any other period in its 56-year history. We used fishery-dependent data, California Department of Fish and Game commercial landing receipts and logbook data, to analyze trends and review the California pink shrimp trawl fishery from 1992 to 2007. In particular, we focus on the most recent years of the fishery (2001–07) to highlight the gear developments and key management measures implemented in the fishery. The fishery is primarily driven by market conditions and is highly regulated by both state and Federal management agencies. Several key regulatory measures implemented during this decade have had significant effects on the fishery. For example, the requirement of a Bycatch Reduction Device on trawl nets targeting pink shrimp was approved in 2001 and has greatly reduced levels of finfish bycatch. Fishery production has declined, particularly in recent years, and may be attributed to decreased market prices, followed by reduced fishermen participation; both of which are related to changes in the processing sector and demand for the product.

Estimating the Economic Impact of the Wild Shrimp, Penaeus sp., Fishery: A Study of Terrebonne Parish, Louisiana

Two approaches are used to estimate the economic impact of domestic wild shrimp, Penaeus sp., fishing in Terrebonne Parish, Louisiana. A 2002 survey of commercial shrimp fishermen in the Parish yields information on sales and operating costs, and results are used to estimate a 1-yr sales effect in the Parish of $36.7 to $128.1 million due to shrimp fishing. In addition, 2001 shrimp ticket sales data ($49.9 million) are input into a REMI (Regional Economic Models, Inc.) model built for the 4-parish bayou region of Louisiana. The REMI model forecasts a year 1 reduction in gross regional product (GRP) of $45.9 million in the 4-parish area if the shrimp fishing industry were to disappear in Terrebonne Parish, and an 8-yr cumulative negative impact on GRP in the bayou region of $191.3 million. Study limitations and suggestions for future research are included.