Dynamic hypoxic zones in Lake Erie compress fish habitat, altering vulnerability to fishing gears

2015 ◽  
Vol 72 (6) ◽  
pp. 797-806 ◽  
Author(s):  
Richard T. Kraus ◽  
Carey T. Knight ◽  
Troy M. Farmer ◽  
Ann Marie Gorman ◽  
Paris D. Collingsworth ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Lake Erie ◽  
Scale Effects ◽  
Stock Assessment ◽  
Fish Habitat ◽  
Fish Distribution ◽  
Commercial Fishing ◽  
Hypoxic Conditions ◽  
Fishing Gears ◽  
Catch Rates

Seasonal degradation of aquatic habitats from hypoxia occurs in numerous freshwater and coastal marine systems and can result in direct mortality or displacement of fish. Yet, fishery landings from these systems are frequently unresponsive to changes in the severity and extent of hypoxia, and population-scale effects have been difficult to measure except in extreme hypoxic conditions with hypoxia-sensitive species. We investigated fine-scale temporal and spatial variability in dissolved oxygen in Lake Erie as it related to fish distribution and catch efficiencies of both active (bottom trawls) and passive (trap nets) fishing gears. Temperature and dissolved oxygen loggers placed near the edge of the hypolimnion exhibited much higher than expected variability. Hypoxic episodes of variable durations were frequently punctuated by periods of normoxia, consistent with high-frequency internal waves. High-resolution interpolations of water quality and hydroacoustic surveys suggest that fish habitat is compressed during hypoxic episodes, resulting in higher fish densities near the edges of hypoxia. At fixed locations with passive commercial fishing gear, catches with the highest values occurred when bottom waters were hypoxic for intermediate proportions of time. Proximity to hypoxia explained significant variation in bottom trawl catches, with higher catch rates near the edge of hypoxia. These results emphasize how hypoxia may elevate catch rates in various types of fishing gears, leading to a lack of association between indices of hypoxia and fishery landings. Increased catch rates of fish at the edges of hypoxia have important implications for stock assessment models that assume catchability is spatially homogeneous.

scholarly journals A multivariate statistical analysis to determine catch intention in the pink cusk-eel (Genypterus blacodes) longline fishery in southern Chile

2020 ◽  
Vol 84 (1) ◽  
pp. 17
Author(s):  
Rodrigo Wiff ◽  
Guillermo Martin Gonzalez ◽  
Francisco Contreras ◽  
Marcelo A. San Martín ◽  
T. Mariella Canales
Keyword(s):  
Stock Assessment ◽  
Principal Component ◽  
Sensitivity Analyses ◽  
Commercial Fishing ◽  
Southern Chile ◽  
Multivariate Statistical ◽  
By Catch ◽  
Catch Rates ◽  
Catch Composition ◽  
Over Time

The definition of catch intention in multispecies fisheries is a key step toward building abundance indexes based on commercial fishing data. Previous analysis to determine catch intention in the pink cusk-eel (Genypterus blacodes) has been based on the idea that fishing tactics remain constant over time (static fishing tactics). We propose a statistical procedure to determine the catch intention of each haul in the industrial longline fisheries in southern Chile, where fishing tactics may vary over time. This procedure is based on principal component analysis and agglomerative hierarchical analysis of the catch composition, and relaxes the assumption of static fishing tactics by selecting a subset of data that is informative for fishing intention (target versus by-catch) every year. Sensitivity analyses were conducted to assess the robustness of variable fishing tactics on the nominal catch rates in pink cusk-eel. Targeted and by-catch time series of nominal catch rates showed a different trend, so determining the catch intention became relevant. Sensitivity analyses showed that trends in targeted catch rates are robust to the variations of fishing tactic per year. We recommend the use of variable fishing tactics for further use in effort standardization and stock assessment of the pink cusk-eel fishery in southern Chile.

scholarly journals Status of Fisheries in Agusan Marsh: Lapaz and Talacogon, Agusan del Sur, Mindanao

2020 ◽  
Vol 27 (1) ◽  
pp. 54-82
Author(s):  
Joyce Baclayo ◽  
Matt Alcantara ◽  
Laila Holoyohoy ◽  
Letecia Alaba
Keyword(s):  
Stock Assessment ◽  
Policy Formulation ◽  
Optimum Level ◽  
Key Species ◽  
Fishing Gears ◽  
Channa Striata ◽  
Policy Measures ◽  
By Catch ◽  
Catch Rates ◽  
High Catch

In support to policy formulation of fisheries in Agusan Marsh, a stock assessment was conducted for the period of May 2014 to December 2016 using the data collected from Lapaz and Talacogon, Agusan del Sur within the Agusan Marsh. Results showed that Lapaz contributed 54% of the catch over Talacogon. A total of eighteen species, belonging to 13 genera and 11 families with 7 native and 11 introduced species were found in the marsh. Majority of the total catch consisted of Channa striata, Oreochromis niloticus, and Cyprinus carpio (35%, 27%, and 26%, respectively). Osphronemus laticlavius, Glossogobius celebius and Mugil cephalus were listed as seasonal species. An invasive janitor fish (Pterygoplichthys disjunctivus) was observed as by-catch. A strong pattern of high catch rates occurred during the rainy months of January, February, June, and December. Ten types of commonly used fishing gears were found, majority of which include fish pots, set gillnets, electrofishing and set long lines. Multivariate analysis showed similarity in species composition both in Lapaz and Talacogon. Exploitation of dominant species showed unsustainable level for O. niloticus, C. batrachus, C. caprio, andC. gariepinus, mainly due to excessive capture of immaturesized fishes by major fishing gears. The estimated exploitation rate is beyond the optimum level for O. niloticus and C. carpio in both years and followed by C. striata and C. gariepinus in 2016. Only C. bartachus is estimated to be exploited below the optimum level. Generally, the key species in Agusan Marsh are at risk of overfishing, hence, immediate policy measures must be given high attention.

scholarly journals Size selectivity and optimal soaking time of hoops and traps targeting the blue swimming crab Callinectes arcuatus in Cuyutlan Lagoon, Mexico

2021 ◽  
Vol 56 (1) ◽  
pp. 42
Author(s):  
Mauricio Salas-Maldonado ◽  
Elaine Espino-Barr ◽  
Emigdio Marín-Enríquez ◽  
Alberto Bartoleño-Sánchez ◽  
Leonardo Daniel Valdez-Carrazco
Keyword(s):  
Carapace Width ◽  
Commercial Fishing ◽  
Fishing Gear ◽  
Swimming Crab ◽  
Size Selectivity ◽  
Soaking Time ◽  
The Third ◽  
Fishing Gears ◽  
Catch Rates ◽  
Swimming Crabs

The selectivity of two types of commercial fishing gear (crab hoop/traditional gear and rigid rectangular cage traps) targeting blue crabs (Callinectes arcuatus) in Cuyutlan Lagoon, Mexico, was assessed. The effect of soak time on crab catches versus the retention and escape rate of organisms was also evaluated. Results suggested that traps captured larger individuals than hoops. The carapace width of crabs was significantly different between the fishing gears used: 63.9% of crabs caught with hoops were < 95 mm (sizes ranged from 40 to 113 mm) and 40.7% of crabs caught with traps were < 95 mm (range: 49 to 120 mm). Results also showed that catch rates were high during the first two hours and decreased after the third hour. The crabs tended to escape after several hours of soak time. The study found that the traps captured larger crabs than the hoops, suggesting that traps are a suitable fishing gear for catching blue swimming crabs in Cuyutlan Lagoon.

scholarly journals Glucose-Limited Fed-Batch Cultivation Strategy to Mimic Large-Scale Effects in Escherichia coli Linked to Accumulation of Non-Canonical Branched-Chain Amino Acids by Combination of Pyruvate Pulses and Dissolved Oxygen Limitation

2021 ◽  
Vol 9 (6) ◽  
pp. 1110
Author(s):  
Ángel Córcoles García ◽  
Peter Hauptmann ◽  
Peter Neubauer
Keyword(s):  
Amino Acids ◽  
Dissolved Oxygen ◽  
Large Scale ◽  
Scale Effects ◽  
Branched Chain Amino Acids ◽  
Oxygen Limitation ◽  
Fed Batch ◽  
Fermentation Products ◽  
Cultivation Strategy ◽  
Branched Chain

Insufficient mixing in large-scale bioreactors provokes gradient zones of substrate, dissolved oxygen (DO), pH, and other parameters. E. coli responds to a high glucose, low oxygen feeding zone with the accumulation of mixed acid fermentation products, especially formate, but also with the synthesis of non-canonical amino acids, such as norvaline, norleucine and β-methylnorleucine. These amino acids can be mis-incorporated into recombinant products, which causes a problem for pharmaceutical production whose solution is not trivial. While these effects can also be observed in scale down bioreactor systems, these are challenging to operate. Especially the high-throughput screening of clone libraries is not easy, as fed-batch cultivations would need to be controlled via repeated glucose pulses with simultaneous oxygen limitation, as has been demonstrated in well controlled robotic systems. Here we show that not only glucose pulses in combination with oxygen limitation can provoke the synthesis of these non-canonical branched-chain amino acids (ncBCAA), but also that pyruvate pulses produce the same effect. Therefore, we combined the enzyme-based glucose delivery method Enbase® in a PALL24 mini-bioreactor system and combined repeated pyruvate pulses with simultaneous reduction of the aeration rate. These cultivation conditions produced an increase in the non-canonical branched chain amino acids norvaline and norleucine in both the intracellular soluble protein and inclusion body fractions with mini-proinsulin as an example product, and this effect was verified in a 15 L stirred tank bioreactor (STR). To our opinion this cultivation strategy is easy to apply for the screening of strain libraries under standard laboratory conditions if no complex robotic and well controlled parallel cultivation devices are available.

Hypoxic tolerance of Chinese black sleeper Bostrichthys sinensis embryos at heartbeat stage

2006 ◽  
Vol 86 (6) ◽  
pp. 1473-1476 ◽  
Author(s):  
Shixi Chen ◽  
Wanshu Hong ◽  
Wei Zhou ◽  
Qiyong Zhang
Keyword(s):  
Dissolved Oxygen ◽  
Exposure Time ◽  
Hypoxic Conditions ◽  
Hypoxic Tolerance ◽  
Heartbeat Rate ◽  
Bostrichthys Sinensis ◽  
Oxygen Concentrations

Tolerance of hypoxia in Chinese black sleeper (Bostrichthys sinensis) embryos at heartbeat stage was examined at different oxygen concentrations. Embryonic response to hypoxic conditions was expressed in terms of the intensity of variation in heartbeat rate (V). Exposure of the embryos at 25°C to 0.5, 1.0 and 1.5 mg/l dissolved oxygen (DO), caused bradycardia, which was developed within the first 10 min of hypoxia, followed by a plateau, and lasted until termination of the hypoxia. The V values were significantly affected by DO concentrations (P<0.01). Exposure of the embryos to 0.2 mg/l DO at 25°C caused a periodic heartbeat (including a period of heartbeat and a period of silence). This phenomenon was first recorded in the present study. During the period of heartbeat, the heartbeat rates were faster at first (147±5 beats per min), and then decreased gradually until the period of silence. As the exposure time increased, the duration of heartbeat was prolonged significantly from 43.4±2.4 second to 126.2±8.2 second (P<0.01), and the duration of silence was also prolonged significantly from 68.0±5.5 second to 247.9±11.5 second (P<0.01). At the beginning of exposure, the primary heartbeat rates displayed tachycardia, and their V values were significantly lower than the V values of average heartbeat rates (P<0.05). However, the V values were not significantly different between primary heartbeat rate and average heartbeat rate after 90 min exposure (P>0.05).

Grenadiers of the World Oceans: Biology, Stock Assessment, and Fisheries

2008 ◽  
Keyword(s):  
Continental Slope ◽  
Ross Sea ◽  
Stock Assessment ◽  
Trawl Survey ◽  
Factors Affecting ◽  
Year Effect ◽  
Macrourus Whitsoni ◽  
Catch Rates ◽  
Potential Methods ◽  
Major Factors

<em>Abstract</em>.—An exploratory longline fishery for toothfish (<em>Dissostichus </em>spp.) in the Ross Sea, Antarctica has been carried out since 1997. The main bycatch species in this fishery is the grenadier, <em>Macrourus whitsoni. </em>No assessments have been carried out of the impact of the fishery on grenadiers, although they have life history characteristics that make them vulnerable to overexploitation. The aims of this research were two-fold; firstly, to characterize the bycatch fishery and to determine factors affecting bycatch rates; and secondly to examine potential methods of monitoring its abundance. A standardized CPUE analysis was used to determine factors affecting bycatch rates of grenadiers in the fishery. The analysis was based on fine-scale haul-by-haul data from all vessels in the fishery from 1999 to 2005. The major factors influencing grenadier bycatch were vessel, area, and depth. Catch rates of grenadiers were highest along the continental slope of the Ross Sea in depths from 600 to 1000 m, and there was an order of magnitude difference in grenadier catch rates between different vessels. Examination of vessel characteristics showed that catch rates of grenadiers were significantly lower with the Spanish line system than with the autoline system. There are several plausible reasons for this difference, including hook location with respect to the seabed, bait type, and differences in levels of reporting of bycatch between vessels. Various approaches to monitoring and assessing grenadiers in the Ross Sea fishery were explored. We conclude that the year effect from the standardized CPUE analysis is unlikely to be monitoring abundance but instead probably reflect changes in gear characteristics, fisher behavior, and targeting of effort. Trends in the length composition of the catch are confounded with depth, and are also of limited value at present. We consider that the best approach to obtaining abundance estimates for grenadiers in the Ross Sea would be to carry out a random bottom trawl survey of the continental slope.

Fish Habitat: Essential Fish Habitat and Rehabilitation

1999 ◽  
Keyword(s):  
Lake Erie ◽  
Habitat Management ◽  
Fish Habitat ◽  
Learning By Doing ◽  
Suitable Habitat ◽  
Physical Habitat ◽  
Fish Stocks ◽  
Habitat Features ◽  
Fish Habitats

<em>Abstract.—</em> The quality and quantity of habitats determine ecosystem productivity. Hence, they determine the potential fish productivity that sustains the fish harvests extractable from freshwaters and seas. Efforts to conserve and protect fish habitats are frustrated by key unanswered questions: which habitat types and how much must be protected to ensure natural self-sustaining fish stocks? Minns and Bakelaar presented a prototype method for assessing suitable habitat supply for fish stocks in Lake Erie, an analysis that can be used to address conservation issues. Here, the method is refined and extended, taking the assessment of habitat supply for pike <em>Esox lucius </em> in the Long Point region of Lake Erie as a case study. As with the previous study, much emphasis is placed on “learning by doing.” Because available inventories of habitat features are coarse and incomplete, improved guidelines for estimating habitat supply are expected from these prototype studies. The habitat supply method previously presented by Minns and Bakelaar is elaborated in three ways here: (1) the basic physical habitat assessment is derived from a remote-sensing inventory database; (2) methods of quantifying the thermal regime and integrating it with other habitat elements are examined; (3) habitat supply estimates are used in a pike population model, and pike biomass and production are simulated for the Long Point region of Lake Erie and then compared with available records. The roles of error and uncertainty are examined for all elements in the estimation and application of suitable habitat supply values. There is potential for supply measurement and analysis to guide fish habitat management.

Fish Habitat: Essential Fish Habitat and Rehabilitation

1999 ◽  
Keyword(s):  
Habitat Suitability ◽  
Polynomial Regression ◽  
Environmental Gradients ◽  
Fish Habitat ◽  
Tampa Bay ◽  
Spotted Seatrout ◽  
Charlotte Harbor ◽  
Biologically Relevant ◽  
Suitability Index ◽  
Catch Rates

<em>Abstract.—</em> A need exists to scientifically determine optimal fish habitats to support decision making for management of essential fish habitat. Scientists have been collaborating to conduct habitat suitability index (HSI) modeling to spatially delineate fish habitats for estuarine fish and invertebrate species in Tampa Bay and Charlotte Harbor, Florida. Results from HSI modeling of juvenile spotted seatrout <em>Cynoscion nebulosus </em> in Charlotte Harbor are presented. Data obtained from 1989–1997 by fisheries-independent monitoring in the two estuaries were used along with environmental data from other sources. Standardized catch-per-unit-effort (catch rates) were calculated across gear types using fisheries-monitoring data from Charlotte Harbor and Tampa Bay. Suitability index functions were determined using three methods: (1) frequency of occurrence, (2) mean catch rates within ranges, and (3) smooth-mean catch rates determined by polynomial regression. Mean catch rates were estimated within biologically relevant ranges and, where sufficient data were available, for finer intervals across environmental gradients. Suitability index functions across environmental gradients were then derived by scaling catch rates. Gridded habitat layers for temperature, salinity, depth, and bottom type in Charlotte Harbor were also created using a geographic information system. Habitat suitability index modeling was conducted using the U.S. Fish and Wildlife Service geometric mean method linked to the ArcView Spatial Analyst module. The model integrated suitability indices associated with the habitat layers for Charlotte Harbor to create a map of the predicted distribution for juvenile spotted seatrout during the fall season. Suitability indices developed for Tampa Bay were used with Charlotte Harbor habitat layers to test transfer of the indices to another estuary. Predicted HSI maps depicted low to optimum habitat suitability zones in Charlotte Harbor. Model performance was evaluated by statistically comparing the relative ranking of mean catch rates with mean suitability indices for corresponding zones. Suitability indices obtained using polynomial regression methods yielded morereliable HSI maps for juvenile spotted seatrout than those derived using mean catch rates within biologically relevant ranges. The observed map, derived using smooth-mean suitability indices transferred from Tampa Bay, was not significantly different (Chi-square goodness-of-fit test) from the expected map derived using smooth-mean indices from Charlotte Harbor. Our modeling efforts using transferred indices indicate that it is possible to predict the geographic distributions of fish species by life stage in estuaries lacking fisheries monitoring.

Integrating catch-at-age and multiyear tagging data: a combined Brownie and Petersen estimation approach in a fishery context

2006 ◽  
Vol 63 (3) ◽  
pp. 534-548 ◽  
Author(s):  
Tom Polacheck ◽  
J Paige Eveson ◽  
Geoff M Laslett ◽  
Kenneth H Pollock ◽  
William S Hearn
Keyword(s):  
Mortality Rate ◽  
Population Size ◽  
Stock Assessment ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Catch Data ◽  
Coefficients Of Variation ◽  
Southern Bluefin Tuna ◽  
Catch Rates ◽  
Comprehensive Framework

A comprehensive framework for modelling data from multiyear tagging experiments in a fishery context is presented that incorporates catch data into the traditional Brownie tag–recapture model. Incorporation of catch data not only allows for improved estimation of natural and fishing mortality rates, but also for direct estimation of population size at the time of tagging. These are the primary quantities required to be estimated in stock assessments — having an approach for directly estimating them that does not require catch rates provides a potentially powerful alternative for augmenting traditional stock assessment methods. Simulations are used to demonstrate the value of directly incorporating catch data in the model. Results from the range of scenarios considered suggest that in addition to providing a precise estimate of population size (coefficients of variation ranging from ~15% to 30%), including catch data can decrease biases in the mortality rate estimates (natural mortality especially) and improve precision of fishing mortality rate estimates (by as much as 60% at age 1). The model is applied to southern bluefin tuna (Thunnus maccoyii) tag–recapture and catch data collected in the 1990s to provide estimates of natural mortality, fishing mortality, and abundance for five cohorts of fish.

Spatial Distribution of Nearshore Fish in the Vicinity of Two Thermal Generating Stations, Nanticoke and Douglas Point, on the Great Lakes

1978 ◽  
Vol 35 (6) ◽  
pp. 885-892 ◽  
Author(s):  
C. K. Minns ◽  
J. R. M. Kelso ◽  
W. Hyatt
Keyword(s):  
Spatial Distribution ◽  
Thermal Stratification ◽  
Lake Erie ◽  
Temperature Response ◽  
Incident Radiation ◽  
Fish Distribution ◽  
Lake Huron ◽  
Vertical Variation ◽  
Pelagic Communities ◽  
Key Words Temperature

At Nanticoke, Lake Erie, 1974, mean fish density varied considerably, range 162–14 204/10 000 m3, as estimated by digital acoustic fish enumeration. At Douglas Point, Lake Huron, 1975, mean density varied less, range 108–671/10 000 m3. At both sites fish densities were generally greatest in the shallowest, 3–5 m, depths. At Nanticoke, where the nearshore has low relief, there were no distinguishable communities. At Douglas Point, where depth increases rapidly offshore, there was evidence of benthic and pelagic communities. There was no evidence of altered fish distribution in relation to temperature. At Nanticoke there was no vertical variation in temperature and no vertical response was to be expected. At Douglas Point there was thermal stratification present in the summer and there was no apparent response. The influence of incident radiation was uncertain because of the effects of diurnal migrations. At both locations fish were clustered horizontally to varying degrees in the spring and fall, while in the summer fish were distributed more evenly. Densest clusters were usually in the vicinity of the turbulent discharge at both locations. The lack of temperature response and the similarity of Nanticoke with situations at nearby streams on Lake Erie suggest that the fish are responding to currents and perhaps topography. Key words: temperature, acoustic enumeration, topography, light

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