Observer-reported skate bycatch in the commercial groundfish fisheries of Alaska

We analyzed skate catch data collected by observers in the North Pacific Groundfish Observer Program (NPGOP) from 1998 through 2008 to document recent changes in the identification of skates by observers and to examine the species composition of observed skate catch in Alaska’s groundfish fisheries as well as recent trends in skate retention by commercial fishermen. Historically, almost all skate bycatch has been reported by NPGOP observers as “skate unidentified.” However, since 2004 observers have been trained to identify skates to the genus and species level. In 2008 over 95% of all skates were identified at least to the genus level, and over 50% were identified to species. The most common species of skates identified by observers in groundfish fisheries are Bathyraja parmifera (Alaska skate), Raja binoculata (big skate), and Bathyraja aleutica (Aleutian skate). Species composition of reported skate catch generally reflects recent survey-derived biomass estimates, with B. parmifera dominating the catches in the Bering Sea and, to a lesser extent, in the Aleutian Islands region, and species of the genus Raja dominating catches in the Gulf of Alaska. A relatively high percentage of the skate catch on longline vessels is still reported at the family or genus level because of difficulties in the identification of skates not brought onboard the vessel. For the larger skate species, the proportion retained for processing has increased in recent years as the market price for skate product has increased. Although observed skate catch does not give a complete account of skate bycatch in the fisheries of the region, observer data provide critical information for the appropriate management of skate populations in Alaska.

Statistical inference about the relative efficiency of a new survey protocol, based on paired-tow survey calibration data

Paired-tow calibration studies provide information on changes in survey catchability that may occur because of some necessary change in protocols (e.g., change in vessel or vessel gear) in a fish stock survey. This information is important to ensure the continuity of annual time-series of survey indices of stock size that provide the basis for fish stock assessments. There are several statistical models used to analyze the paired-catch data from calibration studies. Our main contributions are results from simulation experiments designed to measure the accuracy of statistical inferences derived from some of these models. Our results show that a model commonly used to analyze calibration data can provide unreliable statistical results when there is between-tow spatial variation in the stock densities at each paired-tow site. However, a generalized linear mixed-effects model gave very reliable results over a wide range of spatial variations in densities and we recommend it for the analysis of paired-tow survey calibration data. This conclusion also applies if there is between-tow variation in catchability.

Evaluation of the capture efficiency and size selectivity of four pot types in the prospective fishery for North Pacific giant octopus (Enteroctopus dofleini)

Over 230 metric tons of octopus is harvested as bycatch annually in Alaskan trawl, long-line, and pot fisheries. An expanding market has fostered interest in the development of a directed fishery for North Pacific giant octopus (Enteroctopus dofleini). To investigate the potential for fishery development we examined the efficacy of four different pot types for capture of this species. During two surveys in Kachemak Bay, Alaska, strings of 16 –20 sablefish, Korean hair crab, shrimp, and Kodiak wooden lair pots were set at depths ranging between 62 and 390 meters. Catch per-unit-of-ef for t estimates were highest for sablefish and lair pots. Sablefish pots caught significantly heavier North Pacific giant octopuses but also produced the highest bycatch of commercially important species, such as halibut (Hippoglossus stenolepis), Pacific cod (Gadus macrocephalus), and Tanner crab (Chionoecetes bairdi).

Assessing trends in the density of Atlantic croaker (Micropogonias undulatus): a comparison of passive acoustic and trawl methods

Using data collected simultaneously from a trawl and a hydrophone, we found that temporal and spatial trends in densities of juvenile Atlantic croaker (Micropogonias undulatus) in the Neuse River estuary in North Carolina can be identified by monitoring their sound production. Multivariate analysis of covariance (MA NCOVA) revealed that catch per unit of effort (CPUE) of Atlantic croaker had a significant relationship with the dependent variables of sound level and peak frequency of Atlantic croaker calls. Tests of between-subject correspondence failed to detect relationships between CPUE and either of the call parameters, but statistical power was low. Williamson’s index of spatial overlap indicated that call detection rate (expressed by a 0–3 calling index) was correlated in time and space with Atlantic croaker CPUE. The correspondence between acoustic parameters and trawl catch rates varied by month and by habitat. In general, the calling index had a higher degree of overlap with this species’ density than did the received sound level of their calls. Classification and regression tree analysis identified calling index as the strongest correlate of CPUE. Passive acoustics has the potential to be an inexpensive means of identifying spatial and temporal trends in abundance for soniferous fish species.

Reproductive biology of blue marlin (Makaira nigricans) in the western Pacific Ocean

The reproductive biology of blue marlin (Makaira nigricans) was assessed from 1001 fish (ranging from 121 to 275 cm in eye-to-fork length; EFL) caught by Taiwanese offshore longliners in the western Pacific Ocean from September 2000 to December 2001 and from 843 gonad samples from these fish, The overall sex ratio of the catch was approximately 1:1 dur ing the sampling period, but blue marlin are sexually dimorphic; females are larger than males. Reproductive activity (assessed by histology), a gonadosomatic index, and the distribution of oocyte diameters, indicated that spawning occurred predominantly from May to September. The estimated sizes-at-maturity (EFL50) were 179.76 ±1.01 cm (mean ±standard error) for females and 130 ±1 cm EFL for males. Blue marlin are multiple spawners and oocytes develop asynchronously. The proportion of mature females with ovaries containing postovulatory follicles (0.41) and hydrated oocytes (0.34) indicated that the blue marlin spawned once every 2–3 days on average. Batch fecundity (BF) for 26 females with the most advanced oocytes (≥1000 μm), but without postovulatory follicles, ranged from 2.11 to 13.50 million eggs (6.94 ± 0.54 million eggs). The relationships between batch fecundity (BF, in millions of eggs) and EFL and round weight (RW, kg) were BF = 3.29 × 10 –12 EFL5.31 (r2 = 0.70) and BF = 1.59 × 10–3 RW 1.73 (r2= 0.67), respectively. The parameters estimated in this study are key information for stock assessments of blue marlin in the western Pacific Ocean and will contribute to the conservation and sustainable yield of

Increases in the relative abundance of mid-trophic level fishes concurrent with declines in apex predators in the subtropical North Pacific, 1996–2006

Catch rates for the 13 most abundant species caught in the deep-set Hawaii-based longline fishery over the past decade (1996–2006) provide evidence of a change among the top North Pacific subtropical predators. Catch rates for apex predators such as blue shark (Prionace glauca), bigeye (Thunnus obesus) and albacore (Thunnus alalunga) tunas, shortbill spearfish (Tetrapturus angustirostris), and striped marlin (Tetrapturus audax) declined by 3% to 9% per year and catch rates for four midtrophic species, mahimahi (Coryphaena hippurus), sickle pomfret (Taractichthys steindachneri), escolar (Lepidocybium flavobrunneum), and snake mackerel (Gempylus serpens), increased by 6% to 18% per year. The mean trophic level of the catch for these 13 species declined 5%, from 3.85 to 3.66. A shift in the ecosystem to an increase in midtrophic-level, fast-growing and short-lived species is indicated by the decline in apex predators in the catch (from 70% to 40%) and the increase in species with production to biomass values of 1.0 or larger in the catch (from 20% to 40%). This altered ecosystem may exhibit more temporal variation in response to climate variability.

Modified sorting technique to mitigate the collateral mortality of trawled school prawns (Metapenaeus macleayi)

The potential for changes to onboard handling practices in order to improve the fate of juvenile school prawns (Metapenaeus macleayi) discarded during trawling were investigated in two Australian rivers (Clarence and Hunter) by comparing a purpose-built, water-filled sorting tray against a conventional dry tray across various conditions, including the range of typical delays before the start of sorting the catch (2 min vs. 15 min). Juvenile school prawns (n= 5760), caught during 32 and 16 deployments in each river, were caged and sacrificed at four times: immediately (T0), and at 24 (T24), 72 (T72), and 120 (T12 0) hours after having been discarded. In both rivers, most mortalities occurred between T0 and T24 and, after adjusting for control deaths (<12%), were greatest for the 15-min conventional treatment (up to 41% at T120). Mixed-effects logistic models revealed that in addition to the sampling time, method of sorting, and delay in sorting, the weight of the catch, salinity, and percentage cloud cover were significant predictors of mortality. Although trawling caused some mortalities and comparable stress (measured as L -lactate) in all school prawns, use of the water tray lessened the negative impacts of some of the above factors across both the 2-min and 15-min delays in sorting so that the overall discard mortality was reduced by more than a third. When used in conjunction with selective trawls, widespread application of the water tray should help to improve the sustainability of trawling for school prawns.

The repulsive and feeding-deterrent effects of electropositive metals on juvenile sandbar sharks (Carcharhinus plumbeus)

Reducing shark bycatch and depredation (i.e., damage caused by sharks to gear, bait, and desired fish species) in pelagic longline fisheries targeting tunas and swordfish is a priority. Electropositive metals (i.e., a mixture of the lanthanide elements lanthanum, cerium, neodymium, and praseodymium) have been shown to deter spiny dogfish (Squalus acanthias, primarily a coastal species) from attacking bait, presumably because of interactions with the electroreceptive system of this shark. We undertook to determine the possible effectiveness of electropositive metals for reducing the interactions of pelagic sharks with longline gear, using sandbar sharks (Carcharhinus plumbeus, family Carcharhinidae) as a model species. The presence of electropositive metal deterred feeding in groups of juvenile sandbar sharks and altered the swimming patterns of individuals in the absence of food motivation (these individuals generally avoided approaching electropositive metal closer than ~100 cm). The former effect was relatively short-lived however; primarily (we assume) because competition with other individuals increased feeding motivation. In field trials with bottom longline gear, electropositive metal placed within ~10 cm of the hooks reduced the catch of sandbar sharks by approximately two thirds, compared to the catch on hooks in the proximity of plastic pieces of similar dimensions. Electropositive metals therefore appear to have the potential to reduce shark interactions in pelagic longline fisheries, although the optimal mass, shape, composition, and distance to baited hooks remain to be determined.

Management of fishing capacity in a spiny lobster (Panulirus argus) fishery: analysis of trap performance under the Florida spiny lobster Trap Certificate Program

The spiny lobster (Panulirus argus) fishery in Florida was operationally inefficient and overcapitalized throughout the 1980s. The Trap Certificate Program initiated during the 1992–93 season was intended to increase gear efficiency by reducing the number of traps being used while maintaining the same catch level in the fishery. A depletion model was used to estimate trap fishing efficiency. The costs of fishing operations and the value of the catch were used to determine the revenues generated by the fishery under different trap levels. A negative functional relationship was found between the catchability coefficient and the number of traps, which indicated that the fewer traps operating under the trap reduction scheme were more efficient. Also, the financial analyses indicated that the higher catch efficiency resulting from fewer traps generated significantly higher revenues, despite lower stock abundances. This study indicates that the trap reduction program had improved a situation that would have been much worse.

Evidence of hook competition in longline surveys

Catch rates from surveys are used as indices of abundance for many fish species. Relative abundance estimates from surveys with longline gear do not usually account for possible effects of gear saturation, which potentially creates competition among fish for baited hooks and misrepresentations of abundance trends. We examined correlations between catch rates of sablefish (Anoplopoma fimbria) and giant grenadier (Albatrossia pectoralis) and between sablefish and shortraker (Sebastes borealis) and rougheye rockfish (Sebastes aleutianus) from 25 years of longline surveys in Alaska waters for evidence of competition for hooks. Sablefish catch rates were negatively correlated with giant grenadier catch rates in all management areas in Alaskan waters, and sablefish and rockfish were negatively correlated in five of the six areas, indicating that there is likely competition for hooks during longline surveys. Comparative analyses were done for trawl survey catch rates, and no negative correlations were observed, indicating that the negative correlations on the longline surveys are not due to differing habitat preferences or direct competition. Available adjustments for gear saturation may be biased if the probability of capture does not decrease linearly with baited hooks. A better understanding of each fish species’ catch probabilities on longline gear are needed before adjustments for hook competition can be made.

Habitat and bycatch effects on population parameters of inshore lizardfish (Synodus foetens) in the north central Gulf of Mexico

We examined the effect of habitat and shrimp trawl bycatch on the density, size, growth, and mortality of inshore lizardfish (Synodus foetens), a nonexploited species that is among the most widespread and abundant benthic fishes in the north central Gulf of Mexico. Results of quarterly trawl sampling conducted from spring 2004 through spring 2005 revealed that inshore lizardfish are most abundant on sand habitat, but larger fish are more common on shell rubble habitat. There was no significant difference in fish density between habitats exposed to shrimp trawling on the open shelf versus those habitats within a permitted artificial reef zone that served as a de facto no-trawl area; this finding indicates that either inshore lizardfish experienced minimal effects from trawling or, more likely, that fish moved between trawled and nontrawled habitats. Exploitation ratio (bycatch mortality/total morality) estimates derived from catch curve analysis ranged from 0.43 inside the artificial reef zone to 0.55 outside the reef zone, thus indicating that inshore lizardfish are subject to significant fishing mortality in the north central Gulf of Mexico despite the lack of a directed fishery for the species. We infer from this result that effects of shrimp trawl bycatch may be significant at the population level for nonexploited species and that a broader ecosystem-scale examination of bycatch effects is warranted.

A nursery site of the Alaska skate (Bathyraja parmifera) in the eastern Bering Sea

A nursery site for the Alaska skate (Bathyraja parmifera) was sampled seasonally from June 2004 to July 2005. At the small nursery site (~2 km2), located in a highly productive area near the shelf-slope interface at the head of Bering Canyon in the eastern Bering Sea, reproductive males and females dominated the catch and neonate and juvenile skates were rare. Seasonal samples showed summertime (June and July) as the peak reproductive time in the nursery although some reproduction occurred throughout the year. Timeseries analysis of embryo length frequencies revealed that three cohorts were developing simultaneously and the period of embryonic development was estimated at 3.5 years and average embryo growth rate at 0.2 mm/day. Estimated egg case deposition occurred mainly during summertime and hatching occurred during winter months. Protracted hatching times may be common for oviparous elasmobranch species and may be directly correlated with ambient temperatures as evident from a meta-data analysis. Evidence indicates that the Alaska skate uses the eastern Bering Sea outer continental shelf region for reproduction and the middle and inner shelf regions as habitat for immature and subadults. Skate nurseries may be vulnerable to disturbances because they are located in highly productive areas and because embryos develop slowly.

Distribution of red deepsea crab (Chaceon quinquedens) by size and sex in the Gulf of Mexico

The red deepsea crab (Chaceon quinquedens (Smith, 1879)) has supported a commercial fishery off the coast of New England since the 1970s (Wigley et al., 1975) and has had annual harvests from 400 metric tons (t) (1996) to 4000 t (2001) (NEFMC, 2002). In 2002, a fishery management plan for the northeast fishery on the Atlantic coast was implemented and total allowable catch was reduced to approximately 2500 t (NEFMC, 2002). Although there are management plans for the golden crab (C. fenneri) and the red deep sea crab for Atlantic coast regions, there is no fishery management plan for red deepsea crabs in the Gulf of Mexico. Successful management for sustainable harvests should be based on a knowledge of the life history of the species, but C. quinquedens has been a difficult species for which to obtain life history and abundance information because of its deep distribution.

Desigualdades sociais nas concepções dos professores e estudantes do PROEJA no Instituto Federal de Educação, Ciência e Tecnologia do Sertão Pernambucano - Campus Petrolina-PE

Este trabalho apresenta resultados de uma pesquisa realizada no IFSERTÃO - Instituto Federal de Educação, Ciência e Tecnologia do Sertão Pernambucano a respeito das desigualdades sociais nas concepções dos professores e estudantes do PROEJA. Teve como objetivo analisar e compreender os sentidos produzidos pelos sujeitos da pesquisa sobre as desigualdades sociais e suas perspectivas de superação, considerando seu histórico e seus aspectos atuais. Foi organizado epistemologicamente numa abordagem de pesquisa qualitativa a partir do ponto de vista metodológico do estudo de caso do tipo descritivo e analítico com entrevistas e análise do documento Base do Programa institucionalizado pelo MEC, buscando identificar as aproximações ou distanciamentos entre as concepções dos entrevistados com a proposta do material institucional no que diz respeito às perspectivas de superação das desigualdades no contexto da EJA. O problema da pesquisa foi formulado mediante o seguinte questionamento: Como as desigualdades sociais se apresentam nas concepções dos professores e estudantes do programa e quais suas perspectivas de superação? Para estudo do problema, procedeu-se à imersão no campo empírico da pesquisa com abordagens e utilização de um roteiro de entrevistas previamente formulado, incluiu-se a leitura flutuante do material coletado e as vozes dos entrevistados foram gravadas, transcritas, lidas e analisadas, buscando a captação do sentido atribuído pelos sujeitos a respeito das desigualdades sociais. Mediante essa trajetória, identificou-se, nas concepções dos sujeitos da pesquisa, que o trabalho se apresenta como centralidade no que se refere às manifestações das desigualdades sociais no contexto da EJA/PROEJA, bem como suas diferentes feições na lógica do sistema capitalista no que se refere a educar para a empregabilidade atendendo às exigências do capital. Assim, considerando que, historicamente, a EJA é uma modalidade de ensino que vem sendo ofertada para sujeitos que tiveram seus percursos escolares interrompidos pela condição de trabalhadores, esse tema se configura como estudo de grande relevância no contexto das políticas de Educação de Jovens e Adultos trabalhadores.

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