An assessment of the efficiency of three active fish capture methods and a study of roach / bream hybrids on the Crossens drainage system near Southport.

An assessment of three methods of fish capture, to establish the best fishing method which reflects the best range of sizes and species of fish in a given area. The methods used were trawl netting, electrofishing, and seine netting which were assessed on the Crossens drainage system near Southport. The report also includes a study of roach / bream hybrids that were found at the site, which focuses on their distinguishing features and compared with the features of roach and bream.

The vulnerability of reproductively active squaretail coralgrouper (Plectropomus areolatus) to fishing

Squaretail coralgrouper (Plectropomus areolatus) were captured and tagged at a fish spawning aggregation (FSA) site with conventional and acoustic tags to assess their vulnerability to fishing and spatial dynamics during reproductive periods. Males outnumbered females in catch and, on average, were larger than females. Findings revealed a high vulnerability to fishing, particularly during reproductive periods, and most fish were recaptured within the 5-month spawning season and within 10−12 km of the aggregation site. Individual and sex-specific variability in movement to, and residency times at, the FSA site indicates that individual monthly spawning aggregations represent subsets of the total reproductive population. Some individuals appeared to move along a common migratory corridor to reach the FSA site. Sex-specific behavioral differences, particularly longer residency times, appear to increase the vulnerability of reproductively active males to fishing, particularly within a FSA, which could reduce reproductive output. Both fishery-dependent and fishery-independent data indicate that only males were present within the first month of aggregation. The combined results indicate that reproductively active P. areolatus are highly vulnerable to fishing and that FSAs and migratory corridors of reproductively active fish should be incorporated into marine protected areas. The capture of P. areolatus during reproductive periods should be restricted as part of a comprehensive management strateg

Efecto del glifosato en la morfologia del tubo dogestivo y en la actividad acetilcolinesterasa de la lombriz Eisenia fetida

[EUS] Gaur egun produktu kimiko ugari erabiltzen dira nekazaritzaren produktibitatea emendatzeko eta modu honetan nekazaritza-produktuen etekin eta kalitatea hobetzeko asmoz. Hala ere, produktu kimiko hauek ekosisteman izan ditzaketen hilgarriak ez diren eraginak askotan ez dira kontuan hartzen. Azken urteotan osagai aktibo gisa glifosatoa duten herbiziden erabilera emendatu da. Lan honetan, glifosatoak ingurunean sor ditzakeen eraginak ikertu nahi izan dira, lurzoruan oso ugaria den Eisenia fetida zizarea adierazle biologiko gisa erabiliz. Esperimentuan 10 indibiduo helduz osaturiko 4 populazio erabili ziren, zeinak 14 egunez tratamendu desberdinetan ezarri ziren (kontrola, 50, 500 eta 5000 mg glifosato/Kg lur lehor). Glifosato kontzentrazio desberdinek ez zuten zizareen hilkortasunean edo pisuaren aldaketan eraginik izan. Hala ere, digestio-hodiaren epitelioaren morfologian eta azetilkolinesterasaren jardueran aldaketak behatu ziren. Glifosato kontzentrazio baxueneko ontziko zizareetan digestio-hodiko epitelioaren altueraren uniformetasun falta behatu zen, glifosato kontzentrazio ertaineko ontziko zizareetan orokorrean epitelioaren altuera txikiagoa zen, eta glifosato kontzentrazio handieneko ontziko zizareetan digestio-hodien borobiltasuna eta epitelioaren jarraitasuna galdu zen. Azetilkolinesterasaren jardueraren murrizpena behatu zen glifosatodun lurretan egondako zizareetan. Esperimentu honetan erabilitako glifosato kontzentrazioek zizareengan hilgarriak ez diren aldaketak sortzen dituzte, aztertutako biomarkatzaileak etorkizuneko ekotoxikologia testetan erabilgarriak izan daitezkeelarik.

Making experiment station results more useful to African fish farmers

Rather than using more or less ideal conditions for setting experimental controls, the use of conditions similar to those likely to be encountered by farmers should produce research results which are realistically achievable on the farm. ICLARM has developed an approach to farmer-led experimentation which utilizes a spreadsheet to collate and analyze data collected from participating farmers. The simulation of actual management practices utilized by farmers produced results in replicated on-station trials which were within 11% of net yields on-farm. In addition to giving researchers a tool for comparing farm and station management practices, giving farmers a realistic indication of what yields will be if a technology is adopted should help overcome the problems of disillusionment often encountered when farm results fall below those expected by researchers on the basis of experiment station studies.