Assessment of post-harvest losses in Nigeria fishery: the Kainji Lake model

The paper provides a description of a methodology used for quantitative assessment of post harvest losses in the Kainji Lake Fishery (Nigeria). The sample population was made up of 314 fisherfolk, 115 processors, 125 fish buyers and 111 fish sellers. For the determination of handling losses, 24,839 fishes weighing 2,389.31 kg belonging to 43 species were examined of which 10% by number and 9% by weight deteriorated at checking and 4% by number and 3% by weight at landing. Processing losses recorded 22% by number and 16% by weight deteriorated prior to and during smoking with the traditional 'Banda' kiln. During marketing, 16% of fish sold had deteriorated and 6% by weight of fish bought also deteriorated, mainly due to insect infestation during storage. Based on the 1995 yield estimate for Kainji Lake fishery, approximately 1000 tons of fish estimated at 80 million Naira were lost during handling alone. This figure would be much higher if the level of losses during processing and marketing are included. This assessment technique is recommended for use in obtaining quantifiable data on post harvest losses from other water bodies in Nigeria

Post harvest losses in the fisheries of Kainji Lake

An assessment is given of the post-harvest losses in the Lake Kainji fisheries of Nigeria. The study focussed on quantifiable information on post-harvest technology and post-harvest losses from fisherfolk, fish processors and fish traders operating within the Kainji Lake basin. The information was obtained from questionnaires sent to a total of 665 respondents, comprising 317 fishermen, 115 fish processors, 125 fish buyers, and 111 fish sellers in 45 fishing villages and collection centres within the lake basin. Considering the total catch from gillnets, longlines, traps and cast nets estimated at 14,000 in 1995 about 1,000 t of fish was either discarded or lost value due to spoilage during handling by fisherfolk. Assuming an average prices of 80 Naira/kg of fish, the loss to the economy amounted to 80 million Naira annually. Appropriate recommendations are made to significantly reduce post-harvest losses in the Kainji Lake fishery. (PDF contains 91 pages)

A preliminary investigation into the post harvest losses of fish in Shiroro Lake area

The findings are presented of a study conducted to assess the post harvest losses in Shiroro Lake, Nigeria. The major objectives were to identify and quantify the types of losses, to provide recommendations that would enhance formulation of policy guidelines for utilization and exploitation of the declining fishery resources of the lake

A relational database of post-harvest fish losses

The article describes FISHLOSS, a database of post-harvest fish losses devised by the Natural Resources Institute (NRI), UK. The database contains 450 records of post-harvest fish losses from 150 sources. The majority of the estimates are shelf-life estimates. Designed to be a reference for people studying post-harvest fish losses, it draws attention to areas requiring future research to identify significant losses and the factors which cause them. All researchers and users are encouraged to send NRI their own estimates for inclusion in revised versions of FISHLOSS.

Activity in the pallial nerve of knobbed (Busycon carica) and channeled (Busycotypus canaliculatum) whelks recorded during exposure of the osphradium to odorant solutions

Adult horseshoe crabs (Limulus polyphemus) are the preferred bait in the U.S. east coast whelk pot fishery, but their harvest is being restricted because of severe population declines in the Chesapeake and Delaware bays. To identify other baits, the activity in the pallial nerve of whelks was determined during exposure of the osphradium to odorant solutions prepared from horseshoe crab eggs, horseshoe crab hemolymph, and hard clam (Mercenaria mercenaria) tissue. All three elicited significant responses; bait based on them may provide an alternative to the use of adult horseshoe crabs, although extensive behavioral testing remains to be done. Channeled whelk did not respond to molecular weight fractions (>3 kDa and <3 kDa) prepared from horseshoe crab egg odorant solutions but did respond when the molecular weight fractions were recombined. Whelks appear to have broadly tuned chemoreceptors and manufactured baits may need to mimic the complex mixture of odorants derived from natural sources.

Evaluation of a Pound Net Leader Designed to Reduce Sea Turtle Bycatch

Offshore pound net leaders in the southern portion of Chesapeake Bay in Virginia waters were documented to incidentally take protected loggerhead, Caretta caretta, and Kemp’s ridley, Lepidochelys kempii, sea turtles. Because of these losses, NOAA’s National Marine Fisheries Service (NMFS) in 2004 closed the area to offshore pound net leaders annually from 6 May to 15 July and initiated a study of an experimental leader design that replaced the top two-thirds of the traditional mesh panel leader with vertical ropes (0.95 cm) spaced 61 cm apart. This experimental leader was tested on four pound net sites on the eastern shore of Chesapeake Bay in 2004 and 2005. During the 2 trial periods, 21 loggerhead and Kemp’s ridley sea turtles were found interacting with the control leader and 1 leatherback turtle, Dermochelys coriacea, was found interacting with the experimental leader. Results of a negative binomial regression analysis comparing the two leader designs found the experimental leader significantly reduced sea turtle interactions (p=0.03). Finfish were sampled from the pound nets in the study to assess finfish catch performance differences between the two leader designs. Although the conclusions from this element of the experiment are not robust, paired t-test and Wilcoxon signed rank test results determined no significant harvest weight difference between the two leaders. Kolmogorov-Smirnov tests did not reveal any substantive size selectivity differences between the two leaders.

The Ancillary Harvest of Atlantic Menhaden, Brevoortia tyrannus, Roe on the North Carolina Coast

Gravid Atlantic menhaden, Brevoortia tyrannus, are available along the central coast of North Carolina during the fall and are harvested by the purse-seine fleet from the port of Beaufort. Virtually all of the catch, sexually immature fish included, is reduces to fish meal, fish oil, and fish solubles; however, minor quantities of roe from ripening female menhaden are extracted for local consupmtion. Routine and selective port sampling information was used to characterize the seasonal and biostatistical nautre of the roe menhaden catches at Beaufort. Fishermen recognize two size classes of roe Atlantic menhaden: "forerunners," which are usually the smallest and earliest adult menhaden encountered in the Fall Fishery, and "mammy shad," which are the largest menhaden harvested and produce the greatest roe yields. Roe is extracted from femal fish at various points along the reduction process stream and by several techniques. Vessel cremen and factory personnel extract menhaden roe for personal and local consumption. Undetermined quantities of menhaden roe are channeled into local retail seafood markets. Wholesale prices are about $20 per gallon of roe, while retail prices are about $5 per pound. Carteret County, North Carolina, is probably the only area on the U.S. Atlantic and Gulf coasts where menhaden roe is sold in retail seafood markets. The potential of extracting menhaden roe for foreign markets is discussed

Distribution of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, During June/July 1993–2000

Aerial surveys of belugas, Delphinapterus leucas, in Cook Inlet wre flown each year during June and/or July from 1993 to 2000. This project was designed to delineate distribution and collect aerial counts, elements critical to the managment of this small, isolated stock that was subjected to a persistent harvest by Native hunters. The surveys provided a thorough, annual coverage of the coastal areas of the inlet (1,300 km of shoreline) and included roughly 1,000 km of offshore transects annually. Coastal transects were flown 1.4 km from the waterline, thus surveying most of the area within 3 km of shore. These, along with offshore transects, provided annual systematic searches of 13-33% of the entire inlet. The largest concentration of belugas (151-288 whales by aerial count) was in the northern portion of upper Cook Inlet in the Susitna River Delta and/or in Knik Arm. Another concentration (17-49 whales) was consistently found between Chickaloon River and Point Possession. Smaller groups (generally <20 whales) were occasionally found in Turn-again Arm, Kachemak Bay, Redoubt Bay (Big River), and Trading Bay (McArthur River) prior to 1995 but not thereafter. Over the past three decades, summer distribution has shrunk such that sightings now only rarely occur in lower Cook Inlet and in offshore areas. In the 1990's, most (96-100%) of the sightings were concentrated in a few dense groups in shallow areas near river mouths in upper Cook Inlet.

Harvest History of Belugas, Delphinapterus leucas, in Cook Inlet, Alaska

Belugas, Delphinapterus leucas, in Cook Inlet, Alaska, represent a unique and isolated marine mammal population that has been hunted for a variety of purposes since prehistoric times. Archeological studies have shown that both Alutiiq Eskimos and Dena'ina Atabaskan Indians have long utilized many marine resources in Cook Inlet, including belugas. Over the past century, commercial whaling and sport hunting also occurred periodically in Cook Inlet prior to the Marine Mammal Protection Act of 1972 (MMPA). During the 1990's, the hunting mortality by Alaska Natives apparently increased to 40-70 whales per year, which led to the decling of this stock and its subsequent designation in 2000 as depleted under the MMPA. Concerns about the decline of the Cook Inlet stock resulted in a voluntary suspension of the subsistenc hunt by Alaska Natives in 1999. The difficulty in obtaining accurate estimates for the harvest of these whales is due to the inability to identify all of the hunters and, in turn, the size of the harvest. Attempts to reconstruct harvest records based on hunters' recollections and interviews from only a few households have been subject to a wide degree of speculation. To adequately monitor the beluga harvest, the National Marine Fisheries Service established marking and reporting regulations in October 1999. These rules require that Alaska Natives who hunt belugas in Cook Inlet must collect the lowere left jaw from harvested whales and complete a report that includes date and time of the harvest, coloration of the whale, harvest location, and method of harvest. The MMPA was amended in 2000 to require a cooperative agreement between the National Marine Fisheries Service and Alaska Native organizations before hunting could be resumed.

Water imbibition and thawing losses from frozen prawn meat

Prawn meat which was never in contact with ice or water prior to freezing was frozen at -30°C and was studied up to six months of storage at -23°C for thawing losses and cooked characteristics of the thawed material. Thawing loss was nil in unwashed samples after three days of storage and it gradually increased to 6.6% after 6 months compared to 6.0 and 18.2% in the washed samples during the same periods. It is inferred that the high thawing losses observed in commercial frozen prawn meat immediately after freezing may be mainly an after effect of the water imbibed during the pre-freezing stages. During frozen storage, the changes in texture observed by sensory methods on the cooked product were more in the washed sample indicating that the imbibed water or constituents washed out of the tissue play an important role in textural changes in prawn meat during frozen storage.

Seasonal changes of heat and moisture fluxes from the Caspian Sea surface and its effect on synoptic systems with heavy rainfalls in southern shores of the sea during 2005-2010

Caspian Sea with its unique characteristics is a significant source to supply required heat and moisture for passing weather systems over the north of Iran. Investigation of heat and moisture fluxes in the region and their effects on these systems that could lead to floods and major financial and human losses is essential in weather forecasting. Nowadays by improvement of numerical weather and climate prediction models and the increasing need to more accurate forecasting of heavy rainfall, the evaluation and verification of these models has been become much more important. In this study we have used the WRF model as a research-practical one with many valuable characteristics and flexibilities. In this research, the effects of heat and moisture fluxes of Caspian Sea on the synoptic and dynamical structure of 20 selective systems associated with heavy rainfall in the southern shores of Caspian Sea are investigated. These systems are selected based on the rainfall data gathered by three local stations named: Rasht, Babolsar and Gorgan in different seasons during a five-year period (2005-2010) with maximum amount of rainfall through the 24 hours of a day. In addition to synoptic analyses of these systems, the WRF model with and without surface flues was run using the two nested grids with the horizontal resolutions of 12 and 36 km. The results show that there are good consistencies between the predicted distribution of rainfall field, time of beginning and end of rainfall by the model and the observations. But the model underestimates the amounts of rainfall and the maximum difference with the observation is about 69%. Also, no significant changes in the results are seen when the domain and the resolution of computations are changed. The other noticeable point is that the systems are severely weakened by removing heat and moisture fluxes and thereby the amounts of large scale rainfall are decreased up to 77% and the convective rainfalls tend to zero.