Exploratory Fishing Research Articles

Validating the occurrence of Caribbean reef sharks, Carcharhinus perezi (Poey), (Chondrichthyes: Carcharhiniformes) in the northern Gulf of Mexico, with a key for sharks of the family Carcharhinidae inhabiting the region

Among the sharks inhabiting the continental shelf waters of the western North Atlantic Ocean, those within the genus Carcharhinus are the most speciose (Castro 2011). Authoritative sources agree on the presence of twelve species of carcharhinids in the northern Gulf of Mexico; however, they disagree on the presence of a thirteenth species, C. perezi (Poey), in the region (Compagno 1984, Compagno 2002, McEachran & Fechhelm 1998, Castro 2011). While the range of C. perezi is well-documented to extend from the southeastern coast of Florida and the Bahamas to Brazil (Castro 2011), published records of C. perezi occurring in the northern Gulf of Mexico are limited to two sources. In their description of Eulamia springeri, a junior synonym of C. perezi, Bigelow & Schroeder (1944) place the species in the northern Gulf of Mexico based on “a somewhat shrivelled skin with head” from a specimen collected off the west coast of Florida that was reported by the authors to be “probably of this species.” Later, Springer (1960) reported the capture of a single specimen off the Mississippi River Delta in 1947; however, no detail of the capture was provided other than it being listed within a table summarizing shark species collected during exploratory fishing operations.

Approaches for cytogenetic and molecular analyses of small flow-sorted cell populations from childhood leukemia bone marrow samples

Discordances between minimal residual disease estimates obtained by different methods are a problem in childhood acute lymphoblastic leukemia. We aimed to optimize methods allowing the biological exploration of such discrepancies, i.e. the combination of flow-sorting of small immunophenotypically defined cell populations with subsequent analyses of leukemia-associated cytogenetic and molecular marker. The approaches described here optimize the use of the same tube of unfixed, antibody-stained BM cells for flow-sorting of small cell populations and subsequent exploratory FISH and PCR-based analyses.

Ecología trófica de la Sabaleta Brycon henni (Pisces: Characidae) en el río Portugal de Piedras, Alto Cauca, Colombia

Objetivo. Estudiar la ecología trófica de la sabaleta (Brycon henni) en el río Portugal de Piedras, cordillera Oriental, departamento del Valle del Cauca. Materiales y métodos. Desde octubre de 2008 hasta junio de 2009 se realizaron pescas exploratorias y se determinaron parámetros físico y químicos del hábitat. Los ejemplares capturados fueron eviscerados y el contenido estomacal fue determinado hasta el mínimo taxón posible. Resultados. La especie presenta una dieta generalista que incluye 35 categorías alimenticias, con tendencia al consumo de larvas y ninfas de insectos acuáticos entre los cuales se destacan tricópteros, dípteros y odonatos; también, consume organismos alóctonos al cauce como hormigas (Hymenoptera), escarabajos (Coleoptera) y material vegetal: frutos, semillas y hojas. La relación longitud intestino (LI) vs. longitud estándar (LS) indican que la especie presenta características propias de una especie carnívora (LI = -13.8728 + 1.02377*LS, r= 0.35, n= 22), a su vez, el peso total (PT) depende directamente de la longitud total (LT) y LS del pez (PT = -49.308 + 0.609962*LT; r= 0.92 n=30; PT = -41.6011 + 0.672529*LS; r= 0.89, n=30, respectivamente). Conclusiones. La sabaleta (Brycon henni) presentó caracteristicas de una especie carnivora.

Two new records of uncommon deep-sea perciform fishes from the Southwestern Atlantic

This is the third in a series of reports describing new or rare records caught with circle hooks, a method only recently being employed in exploratory fishing in Brazilian deep waters. Here we report the presence of one family and two species of perciform fishes new to, or never formerly reported from, Brazilian waters: the longfin escolar, Scombrolabrax heterolepis (Scombrolacidae), and the extremely rare ocean bass Verilus sordidus (Acropomatidae). The specimens were collected in outer shelf and slope areas at depths between 300 and 500 meters. Given the rarity of the species reported herein, we also provide an updated diagnosis for each species. We also discuss the need of adequate reports when new records are added to such a large ocean area as the Southwestern Atlantic.

THE ASSESSMENT OF PELAGIC FISH STOCK AND ITS DISTRIBUTIONS IN INDIAN OCEAN BY SPLIT BEAM ACOUSTIC SYSTEM

The assessment of pelagic fish stock and its distribution in Indian Ocean, especially southern part of Java-Bali-Lombok, was conducted by SIMRAD EK-500 Split-beam Acoustic System, in October-November 2001. The research was carried out by R/V Baruna Jaya VII of Indonesia Institute of Science (LIPI), under the Fish Stock Assessment Project in Indonesian Waters of fiscal year 2001. As a result, it can be reported that (I) the dominant species of pelagic fish distributed in this area is small pelagic fish with target strength (TS) values between -54.00 dB to - 37.60 dB, absolute density of between 0.07 to 218 fish/1000 m\ and total fish stock of 526.570 ton/year; (2) the large pelagic fish (some species of tuna) also distributed in the area with average TS of -27 dB, absolute density between 0.00 to 0.07 fish/100 m\ and total fish stock of 386,260 ton/year. This result still needs more accurate verification, especially on the species composition and individual size of fish by a more appropriate biological sampling method (mid-water trawl). Consequently, more acoustical surveys combined with oceanographic sampling and exploratory fishing are needed to evaluate the existing condition of marine fish resources in the area, in order to optimize and set up the relevant and accurate fisheries management plan for suitable and responsible utilization offish resources. Keywords: Split-beam Acoustic System, Fish Stock Assessment, Target Strength, Density, Distribution, Indian Ocean (southern part of Java-Bali-Lombok).

Fuelling the decline in UK fishing communities?

Abstract Abernethy, K. E., Trebilcock, P., Kebede, B., Allison, E. H., and Dulvy, N. K. 2010. Fuelling the decline in UK fishing communities? – ICES Journal of Marine Science, 67: 1076–1085. Volatile fuel prices are a threat to the viability of UK fishing communities. The economic and social impacts of rising fuel costs for fishers and communities in southwest England are examined. Fuel prices doubled between early 2007 and mid-2008, whereas fish prices remained relatively stable throughout as a result of the price-setting power of seafood buyers. It was the fishers who absorbed the increased costs, resulting in significant loss of income, reduced job security, and problems in recruiting crew. All gear types were affected, but fishers using towed gears were most adversely impacted. Fishing vessels with recent investment have greater fuel efficiency, so appeared to be more able to cope and to adapt to increased fuel costs. Fishing behaviour also altered as skippers attempted to increase fuel efficiency at the cost of reduced catches. Most skippers reported fishing closer to port, reducing their exploratory fishing, and ceasing experimentation with fishing gears with lesser environmental impact. Therefore, a threat to fishing community viability may have linked environmental effects. The impacts of this fuel price volatility foreshadow a likely future impact of rising fuel prices attributable to climate change adaptation and mitigation and forecasts of rising oil prices. Without proactive planning and policy development, rising fuel prices have the potential to cause job losses and economic hardship additional to problems that may arise from poor management and stock decline, in all fishing-related sectors of the industry.

First report of rare pomfrets (Teleostei: Bramidae) from Brazilian waters, with a key to Western Atlantic species

This is the first in a series of reports describing new records caught with circle hooks, a method only now being employed in exploratory fishing in Brazilian deep waters. Several new records of deep-water fishes were obtained with this equipment. In this paper we record for the first time the occurrence of two genera and species of Bramidae in Brazilian waters: the tropical pomfret Eumegistus brevorti and the keeltail pomfret Taractes rubescens. We also report on previously unnoticed collection records from preserved specimens of Pterycombus brama in museum collections, and the first capture of an adult bigscale pomfret Taractichthys longipinnis in Brazil. These new records increase the number of bramid species known from Brazilian waters to ten. The addition of P. brama to the Brazilian Bramidae makes the Southwestern Atlantic the only known area of the world where two species of Pterycombus are found together. Meristic, biometric, and new biological data are presented for Eumegistus brevorti. Some species of bramids are rather rare and even if well described in the literature there are morphological characters and behavioral aspects yet to be added. Herein we present detailed descriptions of some bramid species to add to their published descriptions. A key to the Western Atlantic Bramidae is provided.

Seamounts in the southeastern Pacific Ocean and biodiversity on Juan Fernandez seamounts, Chile

Seamounts are vulnerable marine ecosystems. In Chile, information on these ecosystems is quite scarce; thus, a compilation of information on their geographical distribution and biodiversity is presented herein. A total of 118 seamounts distributed in the Chilean EEZ are identified and characterized. Additionally, an in situ assessment was carried out on the Juan Fernandez seamounts 1 and 2 (JF1 and JF2), which were also oceanographically characterized. Phytoplankton, zooplankton, and marine invertebrate samples were collected and an exploratory fishing survey was executed using different gears. According to the bibliographical review, a total of 82 species have been collected on the JF1 and JF2 seamounts, highlighting findings of black coral species caught in lobster traps at the Juan Fernandez Archipelago. Submarine images of the marine substrate at JF1 and JF2 reveal characteristics attributable to the impact of bottom dredges, coinciding with the information obtained from the trawling fleet. The fishing activity was carried out primarily at JF2 (4,667 km of trawling). The monthly fishing effort increased considerably in 2002, 2003, and 2005, reaching values above 500 km of trawling and, thus, modifying the spatial structure of the resource aggregates on the JF2 seamount.

Issues of ecosystem-based management of forage fisheries in “open” non-stationary ecosystems: the example of the sardine fishery in the Gulf of California

The Gulf of California system presents major challenges to the still developing frameworks for ecosystem-based management (EBM). It is very much an open system and is intermittently subject to important influxes of migratory visitors, including large pelagic predatory fishes and small pelagic forage fishes. These migrants include the more tropical species from the coastal ecosystems to the south and perhaps subtropical sardines and anchovies from the California Current upwelling system. In addition to the multi-annual ENSO-scale and what may seem to be rather erratic episodes of major population incursions, the Gulf presents nonstationary, transient aspects on a variety of longer time scales. Moreover, the removal of top predators by commercial and sport fisheries has introduced trends that must be affecting the entire ecosystem, and certainly the forage fishes that are their major prey base. In addition to size limits, fishing seasons, area closures and license limitations, the fishery is managed by an ad hoc adaptive management system, in which the fishing season can be shortened or additional areas closed to fishing if pre-season exploratory fishing surveys indicate a shortage of small pelagic fishes on the fishing grounds. Whether this system is likely to be sustainable in the long term is difficult to determine, given the potential for rapid changes in the system because of environmental changes and/or feedbacks within the food web. Thus it appears that innovative management frameworks, among other things utilizing the comparative method, may be required in order to determine defensible tradeoffs between precaution and resource utilization.

Camarón navaja (Campylonotus semistriatus), crustáceo de aguas profundas frente a la costa central de Chile (Crustacea, Decapoda, Campylonotidae)

During exploratory fishing tasks performed in the continental slope in 2002 and 2003, the presence of the razor shrimp (Campylonotus semistriatus) was detected at depths of 570-682 m (32o10'-34o42'S) and 490-955 m (32o10'-36o00'S) respectively. Cephalothorax lengths between 11 and 37 mm and in 2003 were between 13 and 37 mm, females were larger than males. The variability of average size was explained both by variations in depth and by mean latitude (p < 0.05). Larger individuals toward higher latitudes and between 700 and 800 m depth. Sizes at first sexual maturity were 21.3 and 21.1 mm (cephalothorax length) in 2002 and 2003, respectively. The relationships between length and weight indicated a negative alometry. Catches per unit of area (CPUA) were low, averaging 94.6 and 98.9 kg·km -2 each year. This crustacean, previously reported in the South Atlantic and Pacific as far as 38oS, is now present in the Pacific up to 32oS. Because of its low concentrations at the sea bottom, the fish profiled as a complementary resource for nylon shrimp ( Heterocarpus reedi) or red royal shrimp (Haliporoides diomedeae).

ESTIMACIÓN DE LA ABUNDANCIA DE CAMARÓN CAFÉ (&lt;i&gt;Farfantepenaeus aztecus&lt;/i&gt;) EN LAS COSTAS DE TAMAULIPAS, 2002

Se presentan los resultados de la evaluación de la abundancia de camarón café (Farfantepeneaus aztecus ) en las costas de Tamaulipas durante el verano de 2002. Se realizaron cuatro cruceros de pesca exploratoria en las costas de Tamaulipas en agosto en donde se analizaron los valores de biomasa por área barrida. Estos valores fueron comparados con los obtenidos en cruceros de pesca exploratoria previos. La información fue complementada con datos de la estructura por tallas observadas durante mayo en Laguna Madre y tallas capturadas durante julio en altamar. Los resultados muestran que los rendimientos de la captura y la bio masa existentes son menores a los meses anteriores. Asi mismo, la estructura de tallas en el sistema lagunar, en la costa y la zona lejana a la costa (20 m a 42 m de profundidad) muestran un retraso en el reclutamiento y una desaceleración en el crecimiento, posiblemente como resultado de la anormalidad en la temperatura y la precipitación. Los valores bajos de la bio masa y las tallas observadas provocaron que los rendimientos en las capturas comerciales de altamar fueran menores a lo esperado. Abundance as sessment of brown shrimp (Farfantepenaeus aztecus) in Tamaulipas coasts, 2002 Results from brown shrimp (Farfantepenaeus aztecus ) abundance evaluation of the coasts of Tamaulipas during summer of 2002 are presented. Four exploratory fishing cruises were carried out in the coasts Tamaulipas during August, where bio mass values were analyzed by swept area. These values were compared with data of previous exploratory fishing cruises. The information was complemented with data of size structure, observed during May in Laguna Madre and information from a survey carried out in June 2001. The results shown that the yield of capture and bio mass existing are smaller than the previous months. Likewise, the structure of sizes in the inshore system, from the coast and the distant zone to the coast (20 m to 42 m depth) shown a de lay in the recruit ment and abundance on decrease, possibly explained as a result of a temperature and rain fall abnormality. The low values observed of bio mass and sizes, caused that yields in the commercial captures of open sea were smaller than the expected ones.

Escaping the tyranny of the grid: a more realistic way of defining fishing opportunities

A large part of fishing behavior is choosing where to fish. Trawl skippers usually choose between known fishing opportunities, which are observed as groups of trawls that are conducted in the same portion of a fishing ground, or go exploratory fishing. We outline a simple clustering method based on Euclidean distances between trawls that offers a more realistic way of defining fishing opportunities than grid cells or statistical areas. The resulting cluster tree of trawls is divided into individual groups of trawls (fishing opportunities) using a recommended cut point. Our method correctly classified simulated trawls into fishing opportunities. Fishing opportunities were obtained for vessels in the British Columbia groundfish trawl fishery; each vessel usually fished at a wide variety (mean 26, standard deviation 16, range 2–69) of fishing opportunities. Within each fishing opportunity, trawls generally caught similar species. In the Argentina scallop fishery, our method was able to divide exploratory from regular fishing trawls, with obvious applications for catch-per-unit-effort calculations. Our method could also be used to detect positional errors in data from these fisheries. Fishing opportunities could provide indications of how fishermen might react to marine protected areas and to the imposition of quotas on multispecies fisheries.

Shell morphometric relationships of the most common bivalve species (Mollusca: Bivalvia) of the Algarve coast (southern Portugal)

This study reports shell morphometric relationships (height/length and width/length) for the most common and abundant bivalve species of the Algarve coast (southern Portugal). The individuals were caught during periodic exploratory fishing surveys carried out during 2000 using artisanal fishing gears (clam dredge and razor clam dredge), on soft bottoms in the subtidal zone down to 25 m depth. For this particular study, a total of 7497 bivalves were sampled, belonging to 25 species distributed in 9 Families. Almost all regressions were significant (P<0.05 = 52%) or highly significant (P<0.01 = 44%), the only exceptions being the W/L relationships for two bivalve species (n.s. = 4%). The results revealed that both for height/length and width/length morphometric relationships most species presented positive allometric growth (H/L = 11 species; W/L = 15 species), followed by isometric growth (H/L = 7 species; W/L = 6 species) and by negative allometric growth (H/L = 7 species; W/L = 4 species). Data were compared with some morphometric relationships available for the same species in other geographical areas and several ecological hypotheses or explanations were formulated for the distinct types of growth exhibited by different bivalve species.

Weight–length relationships of 25 bivalve species (Mollusca: Bivalvia) from the Algarve coast (southern Portugal)

Weight–length relationships of some of the most abundant bivalve species from the Algarve coast (southern Portugal) captured during several exploratory fishing surveys carried out during 2000 on a soft bottom in the subtidal zone down to 25 m depth are reported. For this study a total of 7429 individuals were sampled, belonging to 25 bivalve species in nine families. The most represented families were Mactridae and Veneridae with six species, immediately followed by the families Cardiidae (five species) and Donacidae (three species). The results revealed that most species presented isometric (11 species) or positive allometric relationships (11 species), while only a small minority of species displayed negative growth (three species).

Risk aversion in allocating fishing effort in a highly uncertain coastal fishery for pelagic fish, Moluccas, Indonesia

The Ambonese small-scale purse-seine fishery for small pelagic fish, such as scads and mackerels, is characterised by highly variable daily catches. Fishermen involved in this fishery are therefore seriously constrained in optimising the outcome of their fishery through spatial allocation of effort. Spatial patterns in effort allocation were compared with those in catch per unit effort (CPUE), indexed by both catch weight and profit. Average CPUE indexed by catch weight differed between fishing locations by up to 14 times. However, individual fishermen could only detect such large differences after 14 days of exploratory fishing because of the high variability in daily catches. Daily decisions on effort allocation are therefore not based on maximising CPUE but on minimising operational costs and risk. A very high proportion (88%) of the fishing trips were made within 8 km of the home port, although the capacity of the purse seiners allowed for fishing in more productive areas much farther away. A 10- to 20-fold increase in operation costs (travelling and local use rights) when fishing in other areas reinforced this behaviour.

A review of orange roughy Hoplostethus atlanticus fisheries, estimation methods, biology and stock structure

Orange roughy Hoplostethus atlanticus are unusual fish. They form dense aggregations that have fuelled lucrative fisheries at great depths (600–1 400 m), especially off Namibia, New Zealand and Australia. They are thought to be very long-lived (>100 years, maturity at 22–40 years), and to have exceptionally low natural mortality (M = 0.045–0.064 year -1 ) and slow growth rates ( K = 0.055–0.070 year -1 ). In addition, they spawn large eggs and have low fecundity. These factors combine to make orange roughy highly susceptible to overfishing; most stocks are below 30% of pristine levels. Assessments are obtained from indices of catch rate and trawl, acoustic and egg surveys. Acoustic estimates are the most direct, but are confounded by the species' low target strength (-50 to -53 dB) – attributable to the wax-filled swim bladder. Extracellular wax esters are stored in abundance and comprise mostly mono-unsaturated fatty acids, with low concentrations of the &#969-3 fatty acid family. This unusual composition (resultant from the species' diet) ensures neutral buoyancy. Stock separation has been inferred mainly from biological studies, but genetic studies have also found differences among stocks within New Zealand and Australia. Deep-water habitat may be damaged by trawling operations and may take many years to recover, so in some quarters there is a call for a portion of suitable habitat to be set aside for preservation. Although Namibian orange roughy are shallower, smaller and younger than those in other stocks, the Namibian fishery sustained high catches for only a few years before quotas were reduced, from 12 000 to 1 875 tons. Three management lessons are suggested for developing orange roughy fisheries based on the Namibian experience: (1) imposition of catch limits during exploratory fishing; (2) starting the acoustic surveys earlier in the fishery if possible; (3) greater reliance on trends in catch rate until a survey series has been established. Keywords: age determination, aggregations, assessment, biology, diet, distribution, fisheries, genetics, habitat, Hoplostethus atlanticus , lipids, Namibia, orange roughy, reproduction, review, stock structure, surveys African Journal of Marine Science 2001, 23: 181–203

Cephalopod species collected by deepwater exploratory fishing off New England

Federal resources have been used to subsidize exploratory trawling beyond the edge of the continental shelf by refitted New England fishing vessels. Potential targets include deepwater species of fishes, decapod crustaceans, and cephalopods. The first eight cruises of the F/V CONTENDER captured 18 species of cephalopods in 12 families, including four octopods, 11 oegopsid squids, one myopsid squid, and two sepiolids. One additional species of oegopsid squid was collected by jigging from F/V PERSEVERANCE. Of all the species captured, only jigging for Ommastrephes bartramii has much potential for development of a directed cephalopod fishery.

Under ice density and mobility of fish in winter-seining area of two Finnish lakes as revealed by echo-survey

The density and movements of fish under ice were studied with single-beam mobile surveys and fixed location split-beam surveys, as well as exploratory fishing in winter-seining areas of two shallow Finnish lakes during winter 1999. Fish schooled near the bottom during the day but the schools dispersed and fish ascended at night. Single and split-beam target strength distributions corresponded fairly closely with the length distribution of seine catch samples. Estimated fish densities were greater at night than in daylight. The swimming speed of smelt ( Osmerus eperlanus) was 0.18 m·s –1 in daylight and 0.36 m·s –1 at night. The corresponding figures for vendace ( Coregonus albula) were 0.11–0.17 and 0.05–0.08 m·s –1. Nights immediately before and after fishing were the best periods to estimate the effect of seining on fish density. The hydroacoustic fish density estimates at night corresponded closely with seine catches. We conclude that it is possible to estimate the effects of winter-seining by mobile under-ice echo-surveys and catch samples.

Effects of fishing power and competitive interactions among vessels on the effort allocation on the trip level of the Dutch beam trawl fleet

Variations in catch rates in relation to the spatial distribution of beam trawlers were analyzed using mandatory logbook data from the Dutch fleet for 1990-1996. Catch rates by trip, corrected for differences in market value, showed a consistent seasonal pattern with the highest values found during autumn and winter. Catch rates showed a log-linear relationship with engine power, indicating differences in competitive abilities among vessels. In 65% of the fishing trips, catch per unit of effort is equalized among fishing grounds. In the remaining trips, catch rates were below average, suggesting that vessels showed exploratory fishing. These results corroborate predictions of the ideal free distribution theory. More powerful vessels were over-represented on better fishing grounds as compared with less powerful vessels. As a special case the effect of vessel density on catch rate was investigated utilizing the convenient fact that a segment of the Dutch fleet stayed in port during one week each year ('week of prayer'). The catch rate of vessels that continued fishing was 10% higher than in the week before or following the week of prayer. No such differences were observed in a reference area where no change in vessel density was observed. Implications of this evidence of competitive interactions among vessels in relation to fisheries management are discussed. (C) 2000 International Council for the Exploration of the Sea.

Descripción y distribución de cinco crustáceos decápodos recolectados en aguas profundas en torno a las islas Robinson Crusoe y Santa Clara (Archipiélago de Juan Fernández, Chile)

Five decapod crustacean species caught in experimental and exploratory fishing surveys around Robinson Crusoe and Santa Clara islands, Chile (33°38'S, 78°49'W), are identified and described. The fishing operation consisted in setting pots, between 50 and 1000 m depth, from November 1996 to June 1997. The species found were Jasus frontalis (50-100 m), Projasus bahamondei (250 m), Paromola rathbuni (100-300 m), Chaceon chilensis (200-1000 m) and Ovalipes trimaculatus (100 m). The species distribution is discussed, as well as the colonization mechanisms and population renewal of these populations inhabiting islands and submarine mountains of the Southeast Pacific, which are remarkably distant them and from the South American continent.