Genetic diversity in wild stocks of the giant freshwater prawn (Macrobrachium rosenbergii): implications for aquaculture and conservation

The giant freshwater prawn (Macrobrachium rosenbergii) is cultured widely around the world but little is known about the levels and patterns of genetic diversity in either wild or cultured stocks. Studies have suggested that genetic diversity may be relatively low in some cultured stocks due to the history of how they were founded and subsequent exposure to repeated population bottlenecks in hatcheries. In contrast, wild stocks have an extensive distribution that extends from Southern Asia across Southeast (SE) Asia to the Pacific region. Therefore, wild stocks could be an important resource for genetic improvement of culture stocks in the future. Understanding the extent and patterns of genetic diversity in wild giant freshwater prawn stocks will assist decisions about the direction future breeding programs may take. Wild stock genetic diversity was examined using a 472 base-pair segment of the 16S rRNA gene in 18 wild populations collected from across the natural range of the species. Two major clades ("eastern" and "western") were identifi ed either side of Huxley’s line, with a minimum divergence of 6.2 per cent, which implies separation since the Miocene period (5-10 MYA). While divergence estimates within major clades was small (maximum 0.9 per cent), evidence was also found for population structuring at a lower spatial scale. This will be examined more intensively with a faster evolving mtDNA gene in the future.

Descriptions of the U.S. Gulf of Mexico Reef Fish Bottom Longline and Vertical Line Fisheries Based on Observer Data

In July 2006, a mandatory observer program was implemented to characterize the commercial reef fish fishery operating in the U.S. Gulf of Mexico. The primary gear types assessed included bottom longline and vertical line (bandit and handline). A total of 73,205 fish (183 taxa) were observed in the longline fishery. Most (66%) were red grouper, Epinephelus morio, and yellowedge grouper, E. flavolimbatus. In the vertical line fishery, 89,015 fish (178 taxa) were observed of which most (60%) were red snapper, Lutjanus campechanus, and vermilion snapper, Rhomboplites aurorubens. Based on surface observations of discarded under-sized target and unwanted species, the majority of fish were released alive; minimum assumed mortality was 23% for the vertical line and 24% for the bottom longline fishery. Of the individuals released alive in the longline fishery, 42% had visual signs of barotrauma stress (air bladder expansion/and or eyes protruding). In the vertical line fishery, 35% of the fish were released in a stressed state. Red grouper and red snapper size composition by depth and gear type were determined. Catch-per-unit-effort for dominant species in both fisheries, illustrated spatial differences in distribution between the eastern and western Gulf. Hot Spot Analyses for red grouper and red snapper identified areas with significant clustering of high or low CPUE values.

Mortality of Lingcod, Ophiodon elongatus, Related to Capture by Hook and Line

Lingcod, Ophiodon elongatus, were captured by hook and line (sport rod and reel gear and commercial troll gear) at two coastal California locations and held in aquaria for periods of up to 32 days for evaluation of capture-related mortality. Three of 69 lingcod captured with rod and reel gear died of capture-related injuries (4.3% mortality; 95% confidence interval 0–9.3%). None of 15 lingcod captured with troll gear died of capture-related injuries. Due to the low overall mortality rate, there were no discernable trends in mortality with respect to sex, length, depth of capture, and terminal tackle (bait vs. lure). Of 38 fish with visible hooking wounds, 26 showed evidence of wound healing during the holding period.

Analysis of the retailer value chain segment in five governorates

This study is the third output of the SDC-funded “Improving Employment and Income through Development of Egyptian Aquaculture” (IEIDEAS), a three-year project being jointly implemented by the WorldFish Center and CARE International in Egypt with support from the Ministry of Agriculture and Land Reclamation. The aim of the study is to gather data on the retailer segment of the aquaculture value chain in Egypt, namely on the employment and market conditions of the women fish retailers in the five target governorates. In addition, this study provides a case study in Minya and Fayoum of the current income levels and standards of living of this target group. Finally, the study aims to identify the major problems and obstacles facing these women retailers and suggest some relevant interventions.