An investigation into the effects of electric fishing equipment on salmon and sea trout within the area of the Lancashire River Board.

The report looks at experiments into electric fishing equipment and effects on salmon and trout within the Lancashire River Board. Experiments include obtaining information on voltage gradients, ascertaining what damage to fish of the larger size groups resulted from electric fishing, determining whether or not fractures could occur in coarse fish and brown trout,similar to those occurring in salmon and sea trout, and effects low temperatures have on electrofishing techniques.

Assessment of fish populations and habitat on Oculina Bank, a deep-sea coral marine protected area off eastern Florida

A portion of the Oculina Bank located off eastern Florida is a marine protected area (MPA) preserved for its dense populations of the ivory tree coral (Oculina varicosa), which provides important habitat for fish. Surveys of fish assemblages and benthic habitat were conducted inside and outside the MPA in 2003 and 2005 by using remotely operated vehicle video transects and digital still imagery. Fish species composition, biodiversity, and grouper densities were used to determine whether O. varicosa forms an essential habitat compared to other structure-forming habitats and to examine the effectiveness of the MPA. Multivariate analyses indicated no differences in fish assemblages or biodiversity among hardbottom habitat types and grouper densities were highest among the most complex habitats; however the higher densities were not exclusive to coral habitat. Therefore, we conclude that O. varicosa was functionally equivalent to other hardbottom habitats. Even though fish assemblages were not different among management areas, biodiversity and grouper densities were higher inside the MPA compared to outside. The percentage of intact coral was also higher inside the MPA. These results provide initial evidence demonstrating effectiveness of the MPA for restoring reef fish and their habitat. This is the first study to compare reef fish populations on O. varicosa with other structure-forming reef habitats and also the first to examine the effectiveness of the MPA for restoring fish populations and live reef cover.

The potential use of time-area closures to reduce catches of bigeye tuna (Thunnus obesus) in the purse-seine fishery of the eastern Pacific Ocean

Skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), and bigeye (Thunnus obesus) tunas are caught by purse-seine vessels in the eastern Pacific Ocean (EPO). Although there is no evidence to indicate that current levels of fishing-induced mortality will affect the sustainability of skipjack or yellowfin tunas, fishing mortality on juvenile (younger than 5 years of age) bigeye tuna has increased, and overall fishing mortality is greater than that necessary to produce the maximum sustainable yield of this species. We investigated whether time-area closures have the potential to reduce purse-seine bigeye catches without significantly reducing skipjack catches. Using catch and effort data for 1995–2002, we identified regions where the ratio of bigeye to skipjack tuna catches was high and applied simple closed-area models to investigate the possible benefits of time-area closures. We estimated that the most optimistic and operationally feasible 3-month closures, covering the equatorial region of the EPO during the third quarter of the year, could reduce bigeye catches by 11.5%, while reducing skipjack tuna catches by 4.3%. Because this level of bigeye tuna catch reduction is insufficient to address sustainability concerns, and larger and longer closures would reduce catches of this species signficantly, we recommend that future research be directed toward gear technology solutions because these have been successful in many other fisheries. In particular, because over 50% of purse-seine catches of bigeye tuna are taken in sets in which bigeye tuna are the dominant species, methods to allow the determination of the species composition of aggregations around floating objects may be important.

Variation in trawl geometry due to unequal warp length

Survey standardization procedures can reduce the variability in trawl catch efficiency thus producing more precise estimates of biomass. One such procedure, towing with equal amounts of trawl warp on both sides of the net, was experimentally investigated for its importance in determining optimal trawl geometry and for evaluating the effectiveness of the recent National Oceanic and Atmospheric Administration (NOAA) national protocol on accurate measurement of trawl warps. This recent standard for measuring warp length requires that the difference between warp lengths can be no more than 4% of the distance between the otter doors measured along the bridles and footrope. Trawl performance data from repetitive towing with warp differentials of 0, 3, 5, 7, 9, 11, and 20 m were analyzed for their effect on three determinants of flatfish catch efficiency: footrope distance off-bottom, bridle length in contact with the bottom, and area swept by the net. Our results indicated that the distortion of the trawl caused by asymmetry in trawl warp length could have a negative inf luence on flatfish catch efficiency. At a difference of 7 m in warp length, the NOAA 4% threshold value for the 83112 Eastern survey trawl used in our study, we found no effect on the acous-tic-based measures of door spread, wing spread, and headrope height off-bottom. However, the sensitivity of the trawl to 7 m of warp offset could be seen as footrope distances off-bottom increased slightly (particularly in the center region of the net where flatfish escapement is highest), and as the width of the bridle path responsible for flatfish herding, together with the effective net width, was reduced. For this survey trawl, a NOAA threshold value of 4% should be considered a maximum. A more conservative value (less than 4%) would likely reduce potential bias in estimates of relative abundance caused by large differences in warp length approaching 7 m.

Meso-scale transboundary units for the management of coral reefs in the South China Sea area

Local communities and local government units are recognized as the primary stakeholders and participants in the management of coral reef resources and the primary beneficiaries of small-scale fishing activities in the nearshore areas of the coastal zone. The issues relating to the management of the coastal zone are multi-faceted and some issues are largely intertwined with national policy and development goals. Thus, national governments have jurisdiction over these nearshore coastal resources to harmonize policies, monitor resource use and provide incentives for sustainable use. However, the natural boundaries of these reef resources, the processes that support reef ecosystems, and the local or national affiliation of the people who benefit from them may transcend the boundaries of the local and national management units. Therefore, efforts to arrest the decline in fish catch and loss of biodiversity for reefs require management interventions and assessment activities to be carried out at varying scales. In Southeast Asia, some aspects of reef and reef resources management — particularly in deciding the allocation of catch among competing fisheries, development of sustainable harvest strategies, use of broodstock for restocking or stock enhancement programs, protection of nursery and spawning areas, designation of systems of marine protected areas, and the identification of representative, adequate and comprehensive areas for biodiversity conservation in the region — may require the definition of larger management units. At the regional level, multi-country initiatives will need to define units for the transboundary management of resources. The use of large marine ecosystems (LMEs) to identify and manage fisheries resources may be a starting point; however, given the relatively sedentary nature of coral reef-dwelling and reef-associated organisms compared with other pelagic and demersal species, meso-scale transboundary units within the LMEs have to be defined. This paper provides suggestions for transboundary management units for coral reef and reef-associated resources in Southeast Asia based on information from genetic structures of model organisms in the region. In addition, specific reef areas are identified, which may be important beyond their national boundaries, as potential sources of recruits.

Reference area as a factor affecting potential yield estimates of coral reef fishes

A compilation of 48 estimates of Caribbean and Pacific coral reef fish catches, ranging from 0.1 to 23.7 t km super(-2) year super(-1), obtained from coral reef areas ranging from 0.1 to nearly 4-10 super(5) km super(2), are used to show that observed catches, and hence potential yield estimates, depend strongly on the reference area. The implications for coral reef fisheries assessments are discussed.

Bilboko Eraztun Berdeko ekosistemek eskaintzen dituzten zerbitzuen azterketa eta erabiltzaileen pertzepzioa

[EUS] Hiriko ekosistemak garrantzi handiko gune berdeak bilakatzen ari diren honetan, geroz eta gehiago dira eremu naturalen kudeaketarako estrategiak garatzeko biodibertsitatearen eta ekosistemen zerbitzuen balioa kontuan hartu behar dela uste dutenak. Ekosistemen zerbitzuen (gizakiak ekosistematik eskuratzen dituen onurak) kudeaketa jasangarria garatzeko, zerbitzuon eskaintza eta eskaria kontuan hartzen dituzten aspektu biofisiko, sozio-kultural eta ekonomikoak ezagutzea beharrezkoa da. Ikerketa honetan, hiritarrek Bilboko Eraztun Berdeko ekosistemek eskaintzen dituzten zerbitzuen inguruan duten pertzepzioa ezagutu nahi da, jendeak eskaintzen diren zerbitzu guztiak hautematen dituen jakiteko. Horretarako, ikertutako arean ekosistemen hiru zerbitzu kartografiatu dira (aspektu biofisikoa) eta 111 pertsona inkestatu dira euren iritzia ezagutzeko (aspektu sozio-kultural eta ekonomikoa). Hala, ikusi da hiritarrek naturak ongizaterako duen garrantzia ezagutzen dutela, nahiz eta ekosistemen zerbitzuen kontzeptua ez ezagutu. Dena dela, ekosistemak egoera onean mantentzeko prest daude, bereziki garrantzitsuak iruditzen baitzaizkie erregulaziozko zerbitzuak (airearen kalitatea) eta zerbitzu kulturalak (lasaitasuna, aisia, eta naturarekin kontaktua). Beraz, emaitza hauek kontuan hartu beharko lituzkete Bilboko Eraztun Berdeko ekosistemen kudeaketaz arduratzen diren agintariek, etorkizun hurbilean zerbitzuen eskaintza eta eskariaren arteko kudeaketa orekatua garatzeko.

Population parameters of Pennahia anea and Nibea maculata in the Palk Bay/Gulf of Mannar area, India

The population parameters of the two most abundant sciaenids comprising the trawl catch in the Palk Bay/Gulf of Mannar area are presented. The following parameters were estimated: 233 mm (L sub( infinity )), 1.26 yr super(1) (K), -0.08 yr (t sub(0)), 4.24 yr super(1) (Z) and 2.24 yr super(1)(M) for Pennahia anear, 284 mm (L sub( infinity )), 1.08 yr super(1) (K), -0.05 yr (t sub(0)), 4.41 yr super(1) (Z) and 1.92 yr super(1) for Nibea maculata. Length at first capture was 97 mm for P. anea and 124 mm for N. maculata. These lengths were noted to be less than the corresponding length at first maturity for both species. The exploitation rates (E) derived indicate that the two species are heavily fished, which may account for the decline in sciaenid catches from 1988 to 1992.

Number of Players and Relative Pitch Area per Player: Comparing Their Influence on Heart Rate and Physical Demands in Under-12 and Under-13 Football Players

The aim of the present study is to analyse the influence of different large-sided games (LSGs) on the physical and physiological variables in under-12s (U12) and -13s (U13) soccer players. The effects of the combination of different number of players per team, 7, 9, and 11 (P7, P9, and P11, respectively) with three relative pitch areas, 100, 200, and 300 m(2) (A100, A200, and A300, respectively), were analysed in this study. The variables analysed were: 1) global indicator such as total distance (TD); work:rest ratio (W:R); player-load (PL) and maximal speed (V-max); 2) heart rate (HR) mean and time spent in different intensity zones of HR (<75%, 75-84%, 84-90% and >90%), and; 3) five absolute (<8, 8-13, 13-16 and >16 Km h(-1)) and three relative speed categories (<40%, 40-60% and >60% V-max). The results support the theory that a change in format (player number and pitch dimensions) affects no similarly in the two players categories. Although it can seem that U13 players are more demanded in this kind of LSG, when the work load is assessed from a relative point of view, great pitch dimensions and/or high number of player per team are involved in the training task to the U12 players. The results of this study could alert to the coaches to avoid some types of LSGs for the U12 players such as:P11 played in A100, A200 or A300, P9 played in A200 or A300 and P7 played in A300 due to that U13>U12 in several physical and physiological variables (W:R, time spent in 84-90% HRmax, distance in 8-13 and 13-16 Km h(-1) and time spent in 40-60% V-max). These results may help youth soccer coaches to plan the progressive introduction of LSGs so that task demands are adapted to the physiological and physical development of participants.