Effects of temperature on the biology of the northern shrimp, Pandalus borealis, in the Gulf of Maine

Length-frequency data collected from inshore and offshore locations in the Gulf of Maine in 1966-1968 indicated that ovigerous female northern shrimp (Pandalus borealis) first appeared offshore in August and September and migrated inshore in the fall and winter. Once eggs hatched, surviving females returned offshore. Juveniles and males migrated offshore during their first two years of life. Sex transition occurred in both inshore and oll'shore waters, but most males changed sex offshore during their third and fourth years. Most shrimp changed sex and matured as females for the first time in their fourth year. Smaller females and females exposed to colder bottom temperatures spawned first. The incidence of egg parasitism peaked in January and was higher for shrimp exposed to warmer bottom temperatures. Accelerated growth at higher temperatures appeared to result in earlier or more rapid sex transition. Males and non-ovigerous females were observed to make diurnal vertical migrations, but were not found in near- surface waters where the temperature exceeded 6°C. Ovigerous females fed more heavily on benthic molluscs in inshore waters in the winter, presumably because the egg masses they were carrying prevented them from migrating vertically at night. Northern shrimp were more abundant in the southwestern region of the Gulf of Maine where bottom temperatures remain low throughout the year. Bottom trawl catch rates were highest in Jeffreys Basin where bottom temperatures were lower than at any other sampling location. Catch rates throughout the study area were inversely related to bottom temperature and reached a maximum at 3°C. An increase of 40% in fecundity between 1973 and 1979 was associated with a decline of 2-3°C in April-July offshore bottom temperatures. Furthermore, a decrease in mean fecundity per 25 mm female between 1965 and 1970 was linearly related to reduced landings between 1969 and 1974. It is hypothesized that temperature-induced changes in fecundity and, possibly, in the extent of egg mortality due to parasitism, may provide a mechanism which could partially account for changes in the size of the Gulf of Maine northern shrimp population during the last thirty years. (PDF file contains 28 pages.)

Synopsis of biological data on the pink shrimp, Pandalus borealis Kroyer, 1838

This synopsis of the literature was designed to summarize the biological and biochemical studies involving Pandalus borealis as well as to provide a summary of the literature regarding the fisheries data published before early 1984. Included are many unpublished observations, drawn from studies at the State of Maine Department of Marine Resources Laboratory in West Boothbay Harbor, Maine. (PDF file contains 63 pages.)

Configurations and relative efficiencies of shrimp trawls employed in southeastern United States waters

Common shrimp trawl designs employed in the southeastern United States shrimp fishery are the flat, balloon, semiballoon, jib, and super X-3. Recent innovations in trawl design and rigging, including the twin trawl rigging and tongue trawl design, have improved the efficiency of shrimp trawling gear. A description of the construction techniques for the different designs indicate differences which affect gear performance. Measurements of horizontal spread and vertical opening for 76 trawl configurations indicate the relative efficiencies of the different designs. Maximum horizontal spreading efficiency was achieved by the "twin" and "tongue" trawl designs followed by the super X-3, jib, balloon, and semiballoon designs. Designs having the greatest vertical openings were the tongue and flat trawl designs followed by the semiballoon. Maximum total gape dimension was demonstrated by the "Mongoose" tongue trawl. Comparison of trawl spreading efficiency and door area to headrope length ratio indicates that a range of 70-80 in square (per door) of door area is required for each foot of trawl headrope length for maximum efficiency with conventional trawl designs and 66-75 in square per foot of headrope for tongue trawl designs. (PDF file contains 18 pages.)

Identification of West African estuarine shrimp and crab larvae

The paper deals with the decapod crustacean larvae likely to be found in fresh and brackish waters in tropical west Africa. It summarizes results from an ongoing program of describing larvae hatched directly from adults of known species, to provide the identification keys necessary for applied research on nursery grounds, plankton ecology and pollution effects. A preliminary key to stage - 1 larvae is given for approximately 40 species. In includes all the genera, and nearly all the species, known to produce larvae in fresh and low-salinity waters. The common species of higher salinity waters are also included

An economic overview of the fish and shrimp production of the Nigeria fish trawling industry under the structural adjustment programme

Over the years, Nigeria have witnessed different government with different policy measures. Against the negative consequences of the past policies, the structural adjustment was initiated in 1986. Its aims is to effectively altar and restructure the consumption patterns of the economy as well as to eliminate price distortions and heavy dependence on the oil and the imports of consumer goods and services. Within the period of implementation, there has been a decreasing trend in yearly fish catch landings and sizes but the reverse in shrimping. There is also a gradual shift from fishing to shrimping, from the vessels purchased with 83.3% increase of shrimpers from 1985 to 1989. Decreasing fish catch sizes and quantity aggravated by the present high cost of fishing coupled with the favourable export market for Nigeria shrimp tend to influence the sift. This economic situation is the result of the supply measures of SAP through the devaluation of the Naira. There is also overconcentration of vessels on the inshore waters as majority of the vessels are old and low powers hence incapable of fishing on the deep sea. Rotterdam price being paid for automotive gas oil (AGO) by fishing industries is observed to be discriminating and unhealthy to the growth of the industry as it is exceedingly high and unstable thus affecting planning for fishing operation. Fuel alone takes 43% of the total cost of operation. The overall consequences is that fishing days are loss and therefore higher overhead cost. It was concluded that for a healthy growth and sustainable resources of our marine fishery under the structural adjustment programme licensing of new fishing vessels should be stopped immediately and the demand side of SAP should be employed by subsidizing high powered fishing vessels which can operate effectively on the deep sea

Spawning pattern of the Nematopalaemon hastatus (Crustacea: Palaemonidae) (Aurivilius, 1898), exploited in the artisanal shrimp fishery in the outer Cross River estuary

Some aspects of the reproduction of Nematopalaemon hastatus in the artisanal shrimp fishery in the outer Cross River estuary (Nigeria) was investigated. 2 kg samples were taken from the daily catch of the N. hastatus fishery on a twice-weekly basis. The N. hastatus in the sample were then observed for gravidity, using a hand lens, and their post-orbital carapace length (POCL) taken. This was done over a 12-month period. The eggs in formalin-fixed samples showed colour changes from light orange to dark brown with maturation. Gravid females with eggs in different stages of maturation, from light orange to dark brown were observed in the samples. The reproduction occurs all year-round. The proportion of gravid females observed in samples had two distinct peaks in June and November, and two distinct troughs in May and October. The lowest length at which gravidity was observed was 6.0 mm POCL. There were no Penaeus notialis in the samples

Survey of the shrimp stocks of the Sierra Leone inshore shelf : a summary report outlining objectives, observations and recommendations on the status of the Sierra Leone shrimp fishery

This report gives the species and catch-rates per hour of some commercial shrimp species caught in the course of a short survey of inshore shelf fishing grounds. Species seen in significant quantities were: Parapenneopsis atlantica, Parapenaeus longirostris, Penaeus kerathurus and Penaeus duorarum notialis

Synopses of research on shrimps: 1. The common shrimp species of Sierra Leone's coastal waters: their distribution, abundance and size composition

The authors present quantitative information on the shrimp resources of Sierra Leone waters. Four of the nine species present have been studied, of which Paenaeus duorarum notialis is dominant in the fishery. Synoptic surveys were undertaken in June 1977, and March 1978, to determine the abundance of the shrimp stock on the inshore shelf. The temperature-salinity-depth curves for the fishing ground show the existence of three water masses. The majority of fish caught were sciaenids, with some sparids also being taken. Detailed discussion of distribution and abundance of individual species of shrimp is given. The surveys have shown that the Banana Islands are the most productive shrimp grounds in the country, and the authors believe that they can support a viable shrimp industry for several years to come at present rates of exploitation

Size composition of the catches of the pink shrimp Penaeus duorarum notialis in the shrimp fishery of Sierra Leone

Measurements were taken of size distribution of P. d. notialis collected off Sierra Leone over a period of six months from October 1977 to March 1978. From the frequency distribution curves it is observed that the curves for male shrimps show only one or two major modes, which show prominence between 12.5 and 14.1 cm of total length. Females mostly exhibited size groups with three or four different length ranges and occasional occurrence of 1 to 5 modes. These size groups were observed to show continuous changes. No one group could be said to be permanent. The point of entry into the fishery of male shrimps was found to be at an average total length of 10.5 cm, while females did so at 11 cm. Sex ratios in the different samples were usually 1:1 but in one case the males were more numerous by 2:1 and in four other samples females were significantly preponderent. These departures from the 1:1 ratio may have been artificially created by sorting of the catches on board the ships.

White spot syndrome virus (WSSV) transmission risk through infected cooked shrimp products assessed by polymerase chain reaction (PCR) and bio-inoculation studies

The aim of the study was to evaluate the resistance of white spot syndrome virus (WSSV) in shrimps (Penaeus monodon) to the process of cooking. The cooking was carried out at 1000C six different durations 5, 10, 15, 20, 25 and 30 min. The presence of WSSV was tested by single step and nested polymerase chain reaction (PCR). In the single step PCR, the primers 1s5 & 1a16 and IK1 & IK2 were used. While in the nested PCR, primers IK1 &IK2 – IK3 & IK4 were used for the detection of WSSV. WSSV was detected in the single step PCR with the primers 1s5 and 1a16 and the nested PCR with the primers IK1 and IK2 – IK3 & IK4 from the cooked shrimp samples. The cooked shrimps, which gave positive results for WSSV by PCR, were further confirmed for the viability of WSSV by conducting the bio-inoculation studies. Mortality (100%) was observed within 123 h of intra-muscular post injection (P.I) into the live healthy WSSV-free shrimps (P. monodon). These results show that the WSSV survive the cooking process and even infected cooked shrimp products may pose a transmission risk for WSSV to the native shrimp farming systems.

Mississippi River sustenance of brown shrimp (Farfantepenaeus aztecus) in Louisiana coastal waters

Brown shrimp (Farfantepenaeus aztecus) are abundant along the Louisiana coast, a coastline that is heavily influenced by one of the world’s largest rivers, the Mississippi River. Stable carbon, nitrogen, and sulfur (CNS) isotopes of shrimp and their proventriculus (stomach) contents were assayed to trace riverine support of estuarine-dependent brown shrimp. Extensive inshore and of fshore collections were made in the Louisiana coastal zone during 1999–2006 to document shrimp movement patterns across the bay and shelf region. Results showed an unexpectedly strong role for nursery areas in the river delta in supporting the offshore fishery, with about 46% of immigrants to offshore regions arriving from riverine marshes. Strong river influences also were evident offshore, where cluster analysis of combined CNS isotope data showed three regional station groups related to river inputs. Two nearer-river mid-shelf station groups showed isotope values indicating river fertilization and productivity responses in the benthic shrimp food web, and a deeper offshore station group to the south and west showed much less river inf luence. At several mid-shelf stations where hypoxia is common, shrimp were anomalously 15N depleted versus their diets, and this d15N difference or mismatch may be useful in monitoring shrimp movement responses to hypoxia.

Effects of trawling for ocean shrimp (Pandalus jordani) on macroinvertebrate abundance and diversity at four sites near Nehalem Bank, Oregon

Surveys with a remotely operated vehicle (ROV) at four mudhabitat sites with different histories of ocean shrimp (Pandalus jordani) trawling showed measurable effects of trawling on macroinvertebrate abundance and diversity. Densities of the sea whip (Halipteris spp., P<0.01), the flat mud star (Luidia foliolata, P< 0.001), unidentified Asteroidea (P<0.05), and squat lobsters (unidentified Galathoidea, P<0.001) were lower at heavily trawled (HT) sites, as was invertebrate diversity based on the Shannon-Wiener index. Sea cucumbers (unidentified Holothuroidea) and unidentified corals (Hydrocoralia) were observed at lightly trawled (LT) sites but not at HT sites. Hagfish (Eptatretus spp.) burrows were the dominant structural feature of the sediment surface at all sites and were more abundant at the HT sites (P<0.05), a result potentially related to effects from fishery discards. Substantial heterogeneity was found between the northern and southern site pairs, indicating high site-to-site variability in macroinvertebrate densities in these deep (146–156 m) mud habitats. Two of the study sites were closed to trawling in June 2006. The data from this study can be used in combination with future surveys to measure recovery rates of deep, mud, seaf loor habitats from the effects of trawling, thus providing a critical piece of information for ecosystem-based management.

Morphometric differentiation in small juveniles of the pink spotted shrimp (Farfantepenaeus brasiliensis) and the southern pink shrimp (F. notialis) in the Yucatan Peninsula, Mexico

The morphometric and morphological characters of the rostrum have been widely used to identify penaeid shrimp species (Heales et al., 1985; Dall et al., 1990; Pendrey et al., 1999). In this setting, one of the constraints in studies of penaeid shrimp populations has been the uncertainty in the identification of early life history stages, especially in coastal nursery habitats, where recruits and juveniles dominate the population (Dall et al., 1990; Pérez-Castañeda and Defeo, 2001). In the western Atlantic Ocean, Pérez-Farfante (1969, 1970, 1971a) described diagnostic characters of the genus Farfantepenaeus that allowed identification of individuals in the range of 8−20 mm CL (carapace length) on the basis of the following morphological features: 1) changes in the structure of the petasma and thelycum; 2) absence or presence of distomarginal spines in the ventral costa of the petasma; 3) the ratio between the keel height and the sulcus width of the sixth abdominal somite; 4) the shape and position of the rostrum with respect to the segments and flagellum of the antennule; and 5) the ratio between rostrum length (RL) and carapace length (RL/CL). In addition, she classified Farfantepenaeus into two groups according to the shape and position of the rostrum with respect to the segments and flagellum of the antennule and the ratio RL/CL: 1) F. duorarum and F. notialis: short rostrum, straight distally, and the proximodorsal margin convex, usually extending anteriorly to the end of distal antennular segment, sometimes reaching to proximal one-fourth of broadened portion of lateral antennular flagellum, with RL/CL <0.75; and 2) F. aztecus, F. brasiliensis, F. paulensis, and F. subtilis: long rostrum, usually almost straight along the entire length, extending anteriorly beyond the distal antennular segment, sometimes reaching to the distal one-third of broadened portion of lateral antennular flagellum, with RL/CL >0.80. Pérez-Farfante stressed that, for the recognition to species level of juveniles <10 mm CL, all the characters listed above should be considered because occasionally one alone may not prove to be diagnostic. However, the only characters that could be distinguished for small juveniles in the range 4−8 mm CL are those defined on the rostrum. Therefore, it has been almost impossible to identify and separate small specimens of Farfantepenaeus (Pérez-Farfante, 1970, 1971a; Pérez-Farfante and Kensley, 1997).

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.