Catch Weight Research Articles

Evaluation of an acoustical-optical platform for measuring species specific abundance in a weir trap

Data recorded by a bottom mounted survey platform deployed within the opening of a fishing weir were used to calculate absolute abundance estimates for comparison to the weir catch. Species specific abundance estimates were calculated from a combination of sonar and video information recorded by the acoustical-optical platform (AOP). Individual targets were detected in the sonar images using an echo counting technique. Video images were used to provide species identification of acoustic targets within an approximate 10 m range. The number and identification of acoustic targets detected during each deployment was positively correlated with the total catch weights and dominant species in each deployment. The algorithm used to calculate AOP abundance estimates tended to underestimate abundance when more than 50 individuals of the same species were caught and overestimate abundance when less than 50 individuals were caught. Target strength, bearing, and range distributions for individual targets are presented in addition to the species specific percent difference between the AOP estimates and absolute abundances of the weir catch. The agreement between the species specific AOP estimates and absolute abundances of each species indicate that the AOP has the potential to provide data for accurate estimates of multispecies abundance. [Work supported by NOAA.]

Exit Windows as an alternative selective system for the Barents Sea Demersal Fishery for cod and haddock

During a 4-year research period, trouser trawl experiments were performed to assess the cod and haddock selection capacity of a codend fitted with two 130 mm exit windows. These windows, which were 10 meshes high and 45 meshes long, were inserted in the rearmost part of the codend. The results showed that this codend was very efficient in releasing large amounts of undersized fish and the 50% retention length ( l 50) was far above the minimum landing size (MLS) for both the analysed species (the MLS for cod is 47 cm, 44 cm for haddock). For cod, the mean l 50 values varied between 53.6 and 57.3 cm and the mean selection range (SR) values from 6.8 to 9.3 cm. Haddock was measured during two trials with the mean l 50 at 50.5 and 50.6 cm; and the mean SR values at 6.3 and 6.0 cm. Total catch weights varied between 0.7 and 6.6 metric tonnes. In some cases an important effect of catch weights upon the l 50 could be detected.

Fisheries enhancement and biodiversity assessment of fish, prawn and mud crab in Chilika lagoon through hydrological intervention

The degraded state of the fragile ecosystem of Chilika lagoon on the east coast of India caused by natural changes and anthropogenic pressure was in the process of restoration through an effective hydrological intervention during 2000 after thorough scientific investigation including EIA study. The rich fisheries of Chilika lagoon that support livelihood of 0.2 million local fisherfolk was in dwindling state during the eco-degradation phase. Studies on fisheries and fish biodiversity of the lagoon for 4 years before and 4 years after the intervention showed the stark and rapid recovery of fishery immediately after opening of the new mouth with sixfold increase in average annual landing. The average productivity (11.3 t km−2) and CPUE (6.2 kg boat-day−1) during post intervention phase registered 528 and 464% increase, as compared to Pre-intervention years. In total, 277 species of fish and shell fish were documented as occurring in Chilika lagoon before the hydrological intervention. Inventory survey for fish and shell fish species diversity during and after hydrological intervention documented 68 and 97 species, respectively. New records of 56 species of fish and shell fish (7 freshwater, 20 brackishwater and 29 marine) were documented from Chilika lagoon after the hydrological intervention. Analysis of commercial catches showed that the migratory species contributed to the bulk of catches (75% by species and 68% by catch weight). Fish yield and biodiversity seemed to be very sensitive to salinity and hydrologic dynamics of the lagoon. Correlation analysis indicated inverse relationship between water transparency and fish catch (R 2 = 0.715; d.f. = 25; P < 0.01). Positive correlation between salinity and prawn landing (R 2 = 0.542; d.f. = 25; P < 0.01) and salinity and mud crab landing (R 2 = 0.628; d.f. = 25; P < 0.001). Average salinity for the whole lagoon was significantly increased by 42.7% (P < 0.007) as compared to pre-intervention situation. Maintenance of estuarine character of Chilika’s ecosystem particularly the salinity gradient, un-hindered auto-recruitment of fish and shell fish and prevention of destructive fishing are the key factors for fisheries enhancement. Unless carefully planned conservation and regulation measures are ensured with the active participation of local communities during the early phase of restoration, the present scenario of fisheries enhancement may not sustain for longer time.

한국산 중하(Metapenaeus joyneri)의 자원생태학적 특성치 및 자원량

The ecological characteristics and stock biomass of the Shiba shrimp, Metapenaeus joyneri, in Korean waters were determined, using fishery data from the Ministry of Maritime Affairs and Fisheries (MOMAF) and available length frequency data. The instantaneous coefficient of total mortality (Z) of M. joyneri was estimated to be 4.191year, and the annual survival rate (S) was 0.015. The estimated instantaneous coefficient of fishing mortality (F) for recent years was calculated to be 1.94/year. The age at first capture of M. joyneri was 0.71 years. Based on these parameters, the annual biomass of the M. joyneri stock was estimated using a biomass-based cohort analysis and data on the annual catch in weight at age for 1993-2004 in Korean waters. During the study period, the biomass of the shrimp peaked in 1994 at about 9,082 metric tons. Subsequently, it decreased to 500 metric tons in 1998.

Assessing mackerel scad, Decapterus macarellus, in Cape Verde: Using a Bayesian approach to biomass dynamic modelling in a data-limited situation

The fisheries for mackerel scad, Decapterus macarellus, are particularly important in Cape Verde, constituting almost 40% of total catches at the peak of the fishery in 1997 and 1998 (≈3700 tonnes). Catches have been stable at a much lower level of about 2100 tonnes in recent years. Given the importance of mackerel scad in terms of catch weight and local food security, there is an urgent need for updated assessment. Stock assessment was carried out using a Bayesian approach to biomass dynamic modelling. In order to tackle the problem of a non-informative CPUE series, the intrinsic rate of increase, r, was estimated separately, and the ratio B 0/ K, initial biomass relative to carrying capacity, was assumed based on available information. The results indicated that the current level of fishing is sustainable. The probability of collapse is low, particularly in the short-term, and it is likely that biomass may increase further above B msy, indicating a healthy stock level. It would appear that it is relatively safe to increase catches even up to 4000 tonnes. However, the marginal posterior of r was almost identical to the prior, indicating that there is relatively low information content in CPUE. This was also the case in relation to B 0/ K. There have been substantial increases in fishing efficiency, which have not been adequately captured by the measure used for effort (days or trips), implying that the results may be overly optimistic and should be considered preliminary.

Water uptake in herring ( Clupea harengus) and sprat ( Sprattus sprattus) as a function of area, salinity and fat content

When pelagic fish is landed, the total weight includes both fish and water. In Sweden pelagic fisheries for herring ( Clupea harengus) and sprat ( Sprattus sprattus) are allowed to reduce the catch weight with 13% in the Baltic (2003) and 2% in Skagerrak/Kattegat and the North Sea. However, it has also been observed that the weight of individual fish increase due to fish absorb water during storage in the holding tanks onboard fishing vessels. Depending on the magnitude of the water uptake, the catch and landing statistics may be seriously biased. Furthermore, water uptake can also affect our perception of the variations in fish condition related to changes in the environment. Hence in this study, we explore the water uptake in different sized herring and sprat from three areas around the Swedish coast differing in salt concentration. We quantified the water uptake over time in herring and sprat stored fresh in tanks as a function of salinity and fat content. Salinity and fat content was used as covariates since osmotic potential and fat content has been suggested to affect water uptake in fishes. The results indicate that water uptake did not differ between species but did as a function of area and size (length). When exploring the two species separately, water uptake in herring was affected by area and salinity whereas water uptake in sprat by area and size (length). The water uptake difference between the two species was probably related to the stronger relationship between fat content and size (length) in sprat, compared to herring. Overall, the results suggest that the water reduction index used in Sweden as well as other countries should be changed.

How do seaweed farms influence local fishery catches in a seagrass-dominated setting in Chwaka Bay, Zanzibar?

Seaweed farming is often depicted as a sustainable form of aquaculture, contributing to poverty reduction and financial revenues in producer countries. However, farms may negatively affect seagrasses and associated organisms (e.g. invertebrate macrofauna) with possible effects on the flow of ecosystem goods and services to coastal societies. The present study investigates the influence of a seaweed farm, and the farmed seaweed Eucheuma denticulatum in particular, on fishery catches using a traditional fishing method (“madema” basket traps) in Chwaka bay (Zanzibar, Tanzania). The results suggest that a seaweed farm, compared to a seagrass bed, had no influence on catch per unit effort (no. of individuals per catch, or catch weight) or no. of species per catch, but significantly affected catch composition (i.e. how much that was caught of which species). The two species contributing most to differences between the sites were two economically important species; the herbivorous seagrass rabbit fish Siganus sutor, which was more common in the seaweed site and is known to graze on the farmed algae; and the benthic invertebrate feeder chloral wrasse Cheilinus chlorourus, more common in the seagrass site. Compared to vegetation-free bottoms, however, the catches were 3−7 times higher, and consisted of a different set of species (ANOSIM global R > 0.4). As traps placed close to the seaweeds fished three times more fish than traps placed on sand patches within the seaweed farm, the overall pattern is attributed to the presence of submerged vegetation, whether seagrass or seaweed, probably as shelter and/or food for fish. However, qualitative differences in terms of spatial and temporal dynamics between seagrass beds with and without seaweed farms, in combination with other factors such as institutional arrangements, indicate that seaweed farms cannot substitute seagrass beds as fishing grounds.

An investigation of seasonal and annual catches and discards of the Dutch pelagic freezer-trawlers in Mauritania, Northwest Africa

The coastal waters of Northwest Africa (Morocco, Mauritania, Senegal) support a large fishery on small pelagic fish. Super-trawlers from the European Union, mainly of Dutch origin, have exploited these resources since 1996, in particular off Mauritania. This paper reports on the catch and discarding of targeted small pelagic fish by these super-trawlers, based on the results of an independent observer programme that covered 16% of the fleets’ fishing trips during the period 1999–2003. Throughout this period, the average total catch and effort of the fleet was approximately 176,000 t and 1720 days at sea per year, respectively. The target species were Sardinella aurita, Sardinella maderensis, Sardina pilchardus, Scomber japonicus and Trachurus trecae representing an annual average of 94% by weight of the total catches. An alternating seasonal pattern of abundance in the catches was shown for S. aurita (dominant during summer) and S. pilchardus (dominant during winter). The amount of discards on average was less than 10% of the total catch by weight and consisted mainly of commercial species. There was no size selective discarding for the five target species and seasonal changes in discarding were only detected for S. pilchardus. This study suggests that there was no wide scale discarding of pelagic fish by the European super-trawlers from fisheries off Mauritania between 1999 and 2003.

Depth-distribution of deepwater species in Flemish Pass

The depth‐distribution of the main deep‐sea fish species in Divisions 3LMN of the NAFO Regulatory Area is analysed using data from a longline survey carried out between 708 and 3 028 m depths in 1996. The results indicate that the most commercially important deep-sea species, Greenland halibut and roughhead grenadier, were only distributed up to 2 000 m depth. Below this depth another deep-sea species, the armed grenadier, replaced Greenland halibut and roughhead grenadier. The species which showed the widest depth‐distribution were blue antimora, smalleyed rabbitfish and skates (700 m to about 3 000 m). Two species, the roughhead grenadier and the blue antimora, made up more than 60% of the catch in weight. Depth was the factor which most influenced the distribution of the species, affecting both yield and mean length of the catch. Mean length of the catch increased with depth in the majority of species. The yield of all species combined increased with depth between 700 and 1 500 m, where it reached a mean yield of 536 kg per 1 430 hooks. Below this depth the yield diminished.

Seasonal, spatial and gear-related influences on relationships between retained and discarded catches in a multi-species gillnet fishery

A scientific observer program was used to quantify relationships among the compositions and rates of retained and discarded catches taken in a temperate estuarine commercial gillnet fishery in southeastern Australia. Sampling was stratified across six estuaries and three fishing seasons that corresponded to different permitted setting practices (set and immediate retrieve versus overnight set). A total of 265 fishing trips was sampled throughout 2001, yielding 57 species (52 finfish, 3 invertebrate, 1 bird and 1 tortoise), of which 42 and 45 species were retained and discarded, respectively. More species and a greater mean number and weight of total individuals were retained than discarded during each fishing season. Throughout the entire survey, 6.2% by number and 3.3% by weight of catches were discarded. Average retained catches ranged from 37 to 609 kg fisher-day −1 and discarded catches from 1 to 10 kg fisher-day −1. Mugil cephalus and Girella tricuspidata accounted for 85% by number of total observed catches, with a further 10% being contributed by Acanthopagrus australis, Platycephalus fuscus and Portunus pelagicus. G. tricuspidata, A. australis and P. pelagicus below the minimum legal length collectively accounted for 69% by number and 49% by weight of all discards observed. Discarding was greatest in the smallest mesh sizes and during winter when nets can be set overnight. Increasing the minimum permitted mesh size as well as decreasing the maximum soak time of nets set in winter will further reduce the low levels of discarding in this fishery.

Intestinal Behçet disease presenting as neonatal onset chronic diarrhoea in an 11-month-old male baby

Behcet disease is characterised clinically by four major criteria (oral ulcers, genital ulcers, eye lesions, and skin lesions) and six minor criteria (gastrointestinal lesions, thrombophlebitis, cardiovascular lesions, arthritis, central nervous system lesions, and a positive skin pathergy test). We describe an infant with Behcet disease who presented with chronic diarrhoea and recurrent oral ulcers with onset in the neonatal period, which resulted in a prolonged interval between the disease onset and diagnosis. This male baby with a normal perinatal and birth history had non-bloody diarrhoea since the age of 2 weeks. The stools (>10 g/kg/day) were loose and mucoid with a frequency of 3–6 times a day, not responsive to semi-elemental formula feeding. At 3 months of age, the baby had poor body weight gain and anaemia. At the age of 7 months, the baby began experiencing recurrent oral ulcers with fever, which was diagnosed as recurrent herpangina. His body temperature was around 38 C-39 C all day. He was transferred to our hospital at 11 months of age. The physical examination revealed a low body weight (7.7 kg, below the 3rd percentile). One single oral ulcer on the soft palate, and one perianal pustule were noted (Fig. 1A). Maculopapular skin rashes were noted intermittently. High C-reactive protein (27.4 mg/dl) and ESR (45 mm/h) levels were noted. Food allergy tests showed no specific allergy. IgG, IgA, IgM, lymphocyte subset profile, mitogen response and chemoluminesence, C3, C4, antinuclear antibody levels all showed nonspecific findings. Anti-human immunodeficiency virus antibody was non-reactive. Colonoscopy performed at age 13 months showed multiple ulcerations in the whole colon (Fig. 1B). Biopsy revealed a marked neutrophil infiltration in the lamina propria and peri-arterioles. No cryptitis, crypt distortion, or granuloma was noted (Fig. 1C). Ophthalmological examination was normal. HLA-B51 (B5) antigen was negative. Prednisolone (15 mg/day) was given from the age of 14 months and then tapered gradually for 4 months. The body weight caught up to the 50th percentile (Fig. 2). Diarrhoea and anaemia were corrected. Follow-up colonoscopy study at 17 months of age showed a normal appearance. During 3 years of followup, another two episodes of blood-stained diarrhoea, abdominal discomfort with fever and recurrent oral ulcers of the buccal mucosa were observed. Erythematous nodules were noted on the penis and scrotum during further two attacks. The symptoms responded to shortterm prednisolone. C-reactive protein level and ESR were elevated during these episodes (CRP 10.5 mg/dl, ESR 72 mm/h). Juvenile Behcet disease accounts for 3%–7% of all cases of Behcet disease [4]. The rate of intestinal involvement was 68.8% in cases of Japanese children, which was higher than that of adults (16%) [7,10]. Oral lesions and gastrointestinal involvement occur in 31.8% of adult patients. There have been very few reports of Behcet disease in Taiwan [1]. The clinical characteristics of patients differ from those in other Asian countries suggesting that geographic and genetic factors are important in the pathogenesis of the disease [1]. The symptoms of our patient, such as abdominal pain, bloody stools and anal lesions, were similar to those of intestinal Behcet cases in Japan, except for the earlier age at disease onset [4]. A large overlap of clinical manifestations exists between Crohn disease and intestinal Behcet disease including fever, growth failure, oral aphthous ulcers, erythema nodosum, chronic nonspecific inflammatory changes throughout all segments of the gastrointestinal tract and radiological findings [3, 5,9]. Clinical features more favourable to the diagnosis of intestinal Behcet P.-S. Wu AE H.-L. Chen (&) AE Y.-H. Yang P.-I. Lee AE M.-H. Chang Department of Paediatrics, National Taiwan University Hospital, 7F No.7 Chung-Shan S Road, 100 Taipei, Taiwan E-mail: hueyling@ha.mc.ntu.edu.tw Tel.: +886-2-23123456 ext 5148 Fax: +886-2-23934749

Gill-net selectivity off the Portuguese western coast

Abstract Fishing with experimental gill-nets was carried out during 1994 and 1995 off the western coast of Portugal, using mesh sizes between 40 and 90 mm. Most sets were concentrated in the region between Setubal and Lisbon in shallow waters up to 100 m, with about 1/4 being carried out at greater depths. A total of 88 species were captured over the 2 years, of which the majority had small or no commercial value. The most important commercial species (hake, Merluccius merluccius, pouting, Trisopterus luscus, axillary seabream, Pagellus acarne, red mullet, Mullus surmuletus, and horse mackerel, Trachurus trachurus) accounted for about 12% of the catch weight in the 40 mm mesh panels, between 32 and 44% for mesh panels ranging between 60 and 80 mm, and 70% in the 90 mm mesh panels. The estimation of selectivity was carried out for the latter five species and also for the dogfish, Scyliorhinus canicula, wedge sole, Dicologlossa cuneata, and spotted flounder, Citharus linguatula, applying the SELECT method to the data pooled over both years. In the case of hake, pouting and dogfish, sufficient data were available to estimate selectivity on a yearly basis. Four different uni-modal and a bi-modal (bi-normal) models were fitted, with the bi-normal always providing the best fit as given by the smallest value of the ratio deviance/degrees-of-freedom. The exception was the wedge sole where the bi-normal model did not converge and the gamma was the unimodal model providing the best fit. The 40 mm mesh panels mostly retained species of low or no commercial value and undersized hake and pouting. Mesh size panels of 60, 70 and 80 mm proved to be the most efficient in catching the commercially valuable species over the length range available, with virtually no catch of undersized fish. The 90 mm panels retained mainly valuable species, but the overall catches were poor, with the exception of the axillary seabream. These results highlight the difficulties of managing multispecies fisheries based only on mesh size, since the optimal mesh varies considerably among the target species.

Effect of catch size and shape on the selectivity of diamond mesh cod-ends

Abstract An individual-based model that simulates fish selection processes in diamond mesh cod-ends of towed fishing gears is outlined. The model is implemented in a computer program called PRESEMO. A typical simulation can be carried out within a few minutes on a personal computer. Up to four different populations of fish entering the cod-end during a tow can be accounted for. Each fish is assigned a weight, girth, width and height according to its length, and is assumed to have an elliptical cross-section. Fish are allocated a period of travel time down the cod-end, a period for swimming in the cod-end without being exhausted, a period between escape attempts and a packing density for those swimming ahead of the catch. An escape attempt is deemed successful if a fish can pass through the mesh opening at the position in the cod-end where the escape attempt takes place. The mesh opening value is obtained from information on the shape of the cod-end, which depends on the catch weight. The cod-end shape is updated dynamically as the catch builds up during the tow. During a simulation the selection process is continually visualized, that is, the entry, movement and escape attempts of individual fish are shown as well as the changes in the cod-end geometry. At the end of a simulation, a logistic function is automatically fitted to the selection data to obtain estimates of the 50% retention length and the selection range.

서해구 자원관리형 자망 &#x00B7; 통발 어구어법 기술개발에 관한 연구 - 민어 Michthys miiuy 자망의 망목선택성 -

In order to improve the gill nets for croaker, Miichthys miiuy which is proper to the fishermen`s income ans fisheries resource management, we had studied to the net height of present gill nets (mesh size 160mm, 50 mesh in depth), experimental gill nets-I(mesh size 150mm, 68 mesh in depth) and experimental gill nets-II(mesh size 142mm, 75 mesh in depth) in wter using the gill nets design ans analysis simulation system, and then investigated and analyzed the catch efficiency of each gill nets through the field fishing experiments. The net height of emperimental gill nets-I and experimental gill nets-II in water were estimated respectively about 1.5 times and 1.3 times higher than present gill nets which the net height is about 3.5m as the results of simulation considering the current of fishing fields. Total number of croakers which were caught by the persent gill nets was 62(body length 300~1,200mm), total catch weight was 398.7kg (mean 0.6kg/sheet). Total number of croakers which were caught by the experimental gill nets- I was 68(body length 600~1,100mm), total catch weight was 391.6kg (mean 1.2kg/sheet). Total number of croakers which were caught by the experimental gill nets-II was 28(body length 400~900mm), total catch weight was 99.2kg (mean 0.3kg/sheet).

Observaciones sobre la biología de Octopus mimus (Cephalopoda: Octopoda) en la costa peruana

En el presente trabajo se analizan un total de 1339 ejemplares de Octopus mimus Gould, 1852, procedentes de muestreos mensuales realizados en las localidades de Ilo durante el año 1993, Pucusana durante 1997 y en el Callao durante 1998. La relación talla-peso de los ejemplares de Ilo y Callao mostraron un crecimiento alométrico para ambos sexos. Las hembras alcanzan la talla de desove a los 14,3 cm de longitud del manto. Esta talla fue utilizada para estimar un peso mínimo de captura de 1 Kg. La dieta es variable y consiste de crustáceos, moluscos, peces y equinodermos. Las capturas fueron 6 veces más altas durante El Niño 1997-1998 que El Niño 1982-1983. La presente información es comparada y discutida con los datos de Chile.

The effective selectivity of a composite gear for industrial fishing: a sorting grid in combination with a square mesh window

A new gear consisting of a sorting grid in combination with a square mesh window was developed to remedy the bycatch of juvenile gadoids in the industrial fishery for Norway pout ( Trisopterus esmarki ). The purpose of square mesh window was to retain larger marketable fish otherwise sorted out by the grid. Experimental fishing with the composite gear showed improved selectivity of a commercial trawl with catch weight reductions of haddock ( Melanogrammus aeglefinus ) and whiting ( Merlangius merlangus ) of 37 and 57%. Application of these reduction percents to the historical level of industrial bycatch in the North Sea lowered on average the yearly haddock bycatch from 4.3 to 2.7% of the equivalent spawning stock biomass. For whiting the theoretical reduction was from 4.8 to 2.1%. Underlying these results is the deployment of a novel methodology to describe the effective selectivity of composite gears, where the usual descriptors of trawl selectivity, l 50% and SR, do not apply. In order to develop this methodology, fish were collected from three compartments of the gear during the experimental fishing. This experimental set up allowed us first to determine separate selectivity estimates of both the grid and the window and secondly to combine these into estimates of the effective selectivity of the composite gear.

The effective selectivity of a composite gear for industrial fishing: a sorting grid in combination with a square mesh window

A new gear consisting of a sorting grid in combination with a square mesh window was developed to remedy the bycatch of juvenile gadoids in the industrial fishery for Norway pout (Trisopterus esmarki). The purpose of square mesh window was to retain larger marketable fish otherwise sorted out by the grid. Experimental fishing with the composite gear showed improved selectivity of a commercial trawl with catch weight reductions of haddock (Melanogrammus aeglefinus) and whiting (Merlangius merlangus) of 37 and 57%. Application of these reduction percents to the historical level of industrial bycatch in the North Sea lowered on average the yearly haddock bycatch from 4.3 to 2.7% of the equivalent spawning stock biomass. For whiting the theoretical reduction was from 4.8 to 2.1%. Underlying these results is the deployment of a novel methodology to describe the effective selectivity of composite gears, where the usual descriptors of trawl selectivity, l50% and SR, do not apply. In order to develop this methodology, fish were collected from three compartments of the gear during the experimental fishing. This experimental set up allowed us first to determine separate selectivity estimates of both the grid and the window and secondly to combine these into estimates of the effective selectivity of the composite gear.

FISHERY AND OCEANOGRAPHIC MONITORING SYSTEM (FOMS): A NEW TECHNOLOGICAL TOOL BASED ON REMOTE SENSING, WITH APPLICATION IN ECOSYSTEM MANAGEMENT OF COASTAL FISHERIES IN PATAGONIA

The Fishery and Oceanographic Monitoring System (FOMS) or Sistema de Monitoreo Pesquero y Oceanografico (SiMPO) in Spanish, was recently established in San Matias Gulf (Argentina) with the objective of monitoring fishing fleet operations. FOMS was also conceived as a fundamental tool for supporting research activities in the context of the Ecosystem Approach to Fisheries. A detailed description of the system is offered. An on line satellite transceiver (Inmarsat D+) supplies data about position, bearing and speed of the vessels, and alarms are automatically triggered whenever vessels are detected fishing in forbidden areas. The off line module integrating one on board CPU with other components: an electronic logbook allowing to the skipper load data on species catches and effort per haul. An electronic scale integrated to the net bag winch, records gross catch weights and allow calculate by catch and discards. A digital camera records images for control mesh sizes when it is hauled on board, and probes gather data of water temperature and salinity. Sensors in the hold record fish storage temperature in order to certifying quality and traceability chain. All information is stored in a Control Center where ad hoc tools are available for a complete data analysis

Effects of replacement finisher feed and length of feed withdrawal on broiler carcass yield and bacteria recovery

A study was conducted to determine the effects of a replacement finisher feed (RF) on carcass yield and carcass bacteria recovery. RF is a commercial formulation of a D-glucose polymer (maltodextrin) with added salts and vitamins. Commercial male broilers (41 d of age) were given either RF or control-feed (traditional starter feed) for 8 h, followed by feed withdrawal for 0, 4, 8, or 12 h before processing. During processing, whole carcass rinses (WCR) of pre-eviscerated (feathers, feet, and heads removed) and eviscerated carcasses were analyzed for recovery of bacteria. Body weight at initiation of feed withdrawal (catch weight) or at slaughter (dock weight) did not differ significantly due to type of feed. Live shrink, as a percentage of live weight, increased significantly with time off feed. Birds fed RF exhibited significantly lower live shrink than the birds fed the control feed at 8 and 12 h after feed withdrawal. This difference between types of feed, RF or control, was approximately 0.1% per hour of feed withdrawal. Type of feed or length of feed withdrawal did not affect Campylobacter, coliform, or Escherichia coli counts recovered from WCR of pre-eviscerated or eviscerated carcasses. These data demonstrate that feeding RF to broilers for 8 h before initiation of feed withdrawal may reduce live shrink without affecting carcass Campylobacter, coliforms, or E. coli recovered.

Value versus Volume in the Catch of the Spanish South‐Atlantic Trawl Fishery

An understanding of the link between the level of inputs and resultant level of outputs is of considerable importance when trying to manage fisheries through input controls. To this end, studies of several fisheries have been undertaken to examine this relationship through the estimation of production functions and frontiers, using either catch weight or revenue as the dependent variable. The choice of the appropriate output variable to use in the analysis will depend on the objectives of the fishermen. Maximisation of catch weight is often proposed as an objective of fishermen rather than maximisation of profits. In this paper, the technical efficiency scores of vessels operating in the Spanish south‐Atlantic trawl fishery are estimated using the stochastic production frontier approach. The production frontiers are estimated with both the weight and the value of the catch as the dependent variable. The results of the analysis suggest that fishermen adopt a range of strategies but relatively few aim to maximise catch weight only. The differences in strategies may reflect heterogeneous attitudes towards risk, with more risk averse fishermen aiming to trade‐off some potential catch value for a more certain quantity of catch.