Marine Fisheries Management (hosted by AFS)

Contributed Paper Session

8:20AM Global Status of Marine Fisheries and Management Interventions to Reduce Overfishing
Michael Melnychuk, Ray Hilborn
Status of targeted marine fish stocks—generally represented by fishing mortality rate and abundance relative to management targets—is highly variable around the world. Regions with effective fisheries management systems in place, which tend to be well-studied, data-rich regions, generally have fished stocks near management targets on average. In contrast, data-limited regions that typically also have limited management capacity tend to have average stock biomass below target levels and declining while fishing effort is simultaneously increasing. We used hierarchical time series analyses to quantify influence of management interventions on fishing mortality and biomass of >250 assessed stocks. Active rebuilding plans had a strong, rapid effect on lowering fishing mortality to allow overfished stocks to recover, particularly in mixed-species fisheries. Management policies implemented at the stock level—surveys, stock assessments, harvest control rules, catch limits, and individual quotas—were more effective at regulating fishing mortality rates and maximizing equilibrium yield compared to broad policies implemented across species at national, regional, or international levels. Strong fisheries management focussed at the stock level is expected to provide an effective balance between target species abundance and food security objectives.
8:40AM Scallop Dredge Design Using Computational Fluid Dynamics Models and Flume Tank Testing
Liese Siemann, Farrell Davis, Ronald Smolowitz
The Atlantic sea scallop is the focus of one of the most valuable fisheries on the east coast of the United States, but the incidental bycatch of flounder species is impacting the continued sustainability of the fishery. Developing gear modifications to reduce bycatch while maintaining target catch requires many research trips, with each costing hundreds of thousands of dollars due to expensive at-sea testing. Computer simulation packages based on computational fluid dynamics (CFD) offer rapid and inexpensive alternatives to field testing of preliminary gear modifications, and results can be validated using flume tank testing of scaled models. We used both of these methods to improve a low profile dredge designed to reduce flatfish bycatch. A new method for comparing CFD model output to catch data from at-sea trials was also developed. Turbulent eddies predicted by CFD simulations approximated those observed behind scaled models during flume tank testing at matching speeds and bale angles. Furthermore, particle studies from the simulations predicted changes in scallop catch length frequencies and the highly variable fish catch observed during gear trials. Overall, results indicate that CFD simulations and flume tank testing of scaled models are promising new methods for evaluating new scallop dredge designs.
9:00AM Baseline Data on Environmental Impacts on Physiological and Molecular Parameters Determining Growth for Commercially Valuable Decapod Crustacean Management
Anya Byrd, J. Sook Chung
The Blue Crab, Callinectus sapidus, is a model species that is both eurythermal and euryhaline, and can represent many decapod crustaceans. Several biochemical and molecular processes governing the somatic growth have evolved for the survival and success of this species. Understanding these processes will be critical for forecasting population dynamics of the species (and possibly other decapod crustaceans) in a rapidly changing environment. Gathering extensive data on the growth and adaptation, specifically the interaction between the neuroendocrine system for molting (somatic growth) and the mTOR (mammalian target of rapamycin) pathway, can give us information on the degree of stress tolerance in these organisms. A first step in understanding all of this is gathering information on the mTOR pathway and its related genes. The sequences of these related genes, identified from transcriptomic data, will be confirmed. Then the sequences will be examined for the expression levels in animals with different growth rates (size variation) and further analyzed in the whole C. sapidus genome sequence, exploring if there are differences in promoter regions and transcription regulatory sites located in upstream promotor regions.
9:20AM Influence of Traps Equipped with Bycatch Reduction Devices on Blue Crab Catch and Texas Diamondback Terrapin Bycatch
Tiffany Hopper, Pamela Plotkin
The Texas diamondback terrapin (Malaclemys terrapin littoralis) inhabits coastal waters from western Louisiana to Baffin Bay and is a Species of Greatest Conservation Need (SGCN) in Texas. Because terrapins share coastal ecosystems with targets of commercial fisheries like blue crabs (Callinectes sapidus), bycatch mortality in crab traps poses a major threat. Study objectives include testing the impacts of bycatch reduction devices (BRDs) installed in crab traps on bycatch rates of the Texas diamondback terrapin as well as determining impacts of BRDs on blue crab catch in a manner consistent with real-world commercial fishing behavior. Monthly sampling took place at 3 sites in Chocolate Bay near Galveston, Texas in partnership with a commercial crab fisherman. At each location, 18 traps (9 regular and 9 BRD-equipped) were set and checked daily for 3 days with all catch and environmental parameters recorded daily. Sampling for the project is ongoing, but preliminary analyses show patterns in crab catch when comparing regular vs BRD-equipped traps, sampling month, and crab sex as well as monthly patterns in bycatch species.
09:40AM Break
1:10PM Gulf of Mexico Larval Trajectories
Kelly Vasbinder, Cameron Ainsworth, Glenn Zapfe, Robert Weisberg, Yonggang Liu
The Gulf of Mexico (GoM) is home to some of the most economically valuable commercial and recreational fisheries in the United States. Understanding movements of early life stages is a key part of exploring ways to protect fish populations. Larval length at age models were developed from published data sets on larval development. These age models were then used in conjunction with field data to convert larval lengths to ages so that ontogenetic shifts in vertical distribution could be modeled. Generalized additive models were built to predict the concentration of larvae present at depth for a range of age classes and taxa of major commercial and recreational fishes in the Gulf of Mexico based on a suite of environmental variables. These ontogentic vertical migration patterns are now being used in combination with circulation data from the West Florida Coastal Ocean Model (WFCOM) to predict larval trajectories in the Gulf of Mexico. By combining knowledge of depth and the current direction at those depths, larvae can be iteratively tracked through time and a trajectory can be traced. These larval trajectories will be used to inform a larval source and sink matrix for the Gulf of Mexico.
1:30PM Red Snapper Abundance Based on Petersen Mark Recapture Methods
Ana Osowski, Stephen Szedlmayer
Red Snapper, Lutjanus campechanus, abundance was estimated on oil and gas platforms based on Petersen mark-recapture methods in the northern Gulf of Mexico. Abundance estimates were adjusted by applying estimates of emigration, tagging artifact mortality, fisher non-reporting, and tag retention based on a separate Red Snapper telemetry study on the same study platforms. Red Snapper were tagged with Floy internal anchor tags inserted into the peritoneal cavity and released at 20 different platforms on the continental shelf in the northern Gulf of Mexico (Texas, Louisiana, and Alabama) from February 2017 through October 2018. Adjusted Petersen abundance estimates ranged from 147 to 3702 Red Snapper per platform with a mean (±SE) = 967 ± 278. Platforms located closer to shore had significantly higher Red Snapper abundance estimates. Based on the Petersen mean abundance estimate there were 515,411 and 825,500 kg (1.82 mil lbs) of Red Snapper on platforms (n = 533) within the depth range of 18 to 46 m of the present study in the northern Gulf of Mexico.
1:50PM High Reward Tagging Reveals Temporal Variation in Red Snapper Exploitation Under Increasing Recreational Season Length from 2016-2018.
Dana Sackett, Matthew Catalano, Crystal Hightower, Mark Albins, Sean Powers, Marcus Drymon
Changes in fishery management regulations can influence local fishery resources via changes in fishing effort dynamics, and ultimately exploitation rates. For the Red Snapper fishery in the northern Gulf of Mexico, previous management changes resulted in a Federal private-boat recreational fishing season lasting only a few days, causing unrest among fishers. The federal Red Snapper private-boat recreational season was extended in 2017 (from 3 days to 39 days) and 2018 (47 days). Here we examined spatial and temporal changes in recreational Red Snapper exploitation in waters off Alabama using a high reward tag-recapture approach from 2016 to 2018. Our preliminary results showed that exploitation rate estimates did not change in proportion to the increase in the length of the fishing season. The contribution from the charter sector to recreational tag returns declined over time suggesting a downward trend in charter reporting rates. However, sensitivity analysis indicated that our general conclusions regarding temporal trends in exploitation were robust to declining charter participation. These results suggest that more fishing opportunity may not necessarily result in higher exploitation rates. Understanding how exploitation rates and fishers respond to changes in management strategies is vital to understanding the impact of these policies on local fisheries.
2:10PM Classification Criteria of Mature Females of the Bullseye Pufferfish Sphoeroides Annulatus and Its Effect on the Length at First Maturity.
Carolina Salas, Enrique Morales, Hugo Aguirre
Length at first maturity (L50) was calculated for mature females of the bullseye pufferfish Sphoeroides annulatus (Jennys 1842) based on two histological criteria: a) a basic criterion (BC) where the immature females were identified as those showing immature, developing and regenerating phases; and b) based on the gonadotropin dependent phase (GD), where immature organisms are only those that have never spawned. Total length (mm) of 749 females was measured, and maturity phases were determined through histological analysis. Thus, the cumulative frequency distribution was used analyzing mature and immature organisms, and it was fitted to a logistic model and a 95% non-parametric confidence interval (IC95) was estimated resampling the observed data 1500 times for predictions and parameters. For the BC criterion the L50 = 221 mm (IC95 = 202-242), and for GD criterion, L50 = 238 mm (IC95 = 226-256 mm). Results showed that both criteria were correct; however, GD criterion allowed to calculate L50 at any time, without dependence of the reproductive period or spawning peaks.
2:30PM Non-Commercial Catch Estimation for the Main Hawaiian Islands Deep 7 Bottomfish
Hongguang Ma, Tom Ogawa, Annie Yau
Catch estimates from the Hawaii Marine Recreational Fishing Survey (HMRFS) were evaluated to obtain non-commercial catch weight estimates of the Main Hawaiian Islands Deep 7 bottomfish complex, a management grouping of 6 snappers and 1 grouper. Since a significant proportion of the estimated catch numbers did not have corresponding weights, length data from the HMRFS catch survey were used to generate length-based weights from length-weight relationships. The length-based weights and directly measured weights were combined to generate mean weights for the fish with missing weights. Current HMRFS catch estimates are for total catch and do not distinguish between catch to be sold versus catch not for sale. In order to provide a non-commercial catch weight estimate, total estimated catch weight was subsequently adjusted by excluding the proportion of catch claimed to be sold by surveyed fishers. For the most commonly reported Deep 7 bottomfish, the annual non-commercial catch would be significantly overestimated if the proportion of sold catch in HMRFS was not removed. The non-commercial catch weight estimates from this study, in combination with the catch from commercial fishing reports, better define total fishing removal for the Deep 7 bottomfish, and help improve future stock assessments.
2:50PM Refreshment Break
3:20PM No Free Lunch: Estimating the Biomass and Ex-Vessel Value of Target Catch Lost to Depredation By False Killer Whales (Pseudorca Crassidens) in the Hawaii Longline Deep-Set Tuna Fishery.
Joseph Fader, Andrew Read
False killer whales depredate catch and bait of Hawaii deep-set longline fishing vessels, creating an economic cost for the fishery. In addition, catches lost to odontocetes are not included in stock assessments. Observers from the National Marine Fisheries Service monitor 20% of all trips in this fishery and collect data on depredation and bycatch of marine mammals. Depredating odontocetes typically remove the entire fish behind the gills, leaving the head on the gear. Our goal was to estimate the biomass of fish lost to odontocete depredation and associated economic losses to the fishery. Depredation occurred on 6% of sets from 2004-2017 involving a total of 12,577 hooked fish. Most (> 60%) depredated fish were bigeye (Thunnus obesus) or yellowfin (Thunnus albacares) tuna, followed by dolphinfish (Coryphaena spp.), billfish (Istiophoridae spp.), and wahoo (Acanthocybium solandri). We used length-weight relationships to estimate the biomass of bigeye and yellowfin tuna caught and the expected biomass of depredated fish. We estimate an average of 71.8 metric tons (range 45.0 – 104.0 t, sd = 19.0) of tuna was lost to odontocete depredation yearly from 2004-2017, with an average value of USD 840,890 per year from 2012-2017 (range USD 693,910 – 1,025,783, sd = 148,010).
3:40PM Using Citizen Science to Evaluate the Influence of Marine Ornamental Fishery on Hawaiian Reef Fish Occurrence and Abundance
Timothy Grabowski, Anna Baker Mikkelsen
The impact of the marine ornamental fishery on the populations of targeted fishes is a contentious issue. We used volunteer citizen diver fish survey data to evaluate trends in the occurrence and abundance of the most commonly collected reef fish species in areas open to collecting to those in areas where the collection of marine ornamentals is prohibited. Fish surveys were collected by volunteer citizen divers and the most common species of reef fishes exported from Hawaii were identified using customs declarations provided by U.S. Fish and Wildlife Service. For most evaluated species, there was no evidence that being targeted in the marine ornamental fishery influenced their occurrence or reported abundance in volunteer citizen diver surveys. However, two species, Achilles Surgeonfish Acanthurus achilles and Hawaiian Cleaner Wrasse Labroides phthirophagus, did show declines in both occurrence and reported abundance during the study period. The most frequently targeted species seem to have stable or increasing populations, suggesting that these populations are not being overexploited. However, species that are also targeted in subsistence and recreational fisheries or that might exhibit naturally low population densities may warrant special management considerations.
4:00PM The Occupational Health and Safety Predicament in South East Asia: A Case Study of Poor Artisanal Fishing Communities in Indus Basin Arabian Sea Pakistan
Muhammad Naeem Khan
The vast majority of the artisanal fisher lives below the poverty line in shanty and underdeveloped fishing villages along the 990 Km coastline, forming the northern boundary of the Arabian Sea, Pakistan. Coastal mangrove forests provide food and shelter to fish and act as nurseries and feeding grounds for economically important fish species, on which the artisanal fishing communities depend. Any disturbance to this mangrove ecosystem & fish habitat will result in smaller fish population and reduction in marine fish catches. Today, sustainability of artisanal fisheries in Indus basin is threatened by the poor socioeconomic indices of fishing communities, overfishing, mangrove coastal forests destruction, aquatic pollution and other anthropogenic activities by a population exploded to over 200 million. Aquaculture has opened up new avenues for fish production, community development and poverty alleviation in artisanal fishing communities of Pakistan. The paper will give an overview of the plight and the decline of artisanal fisheries in Indus basin Arabian Sea, Pakistan and highlight the importance of the training and other interventions for sustainable fishing and fish production from the alternate source of aquaculture, a badly needed interposition that can save the coastal fishing communities in Pakistan.



Contributed Paper Session
Location: Reno-Sparks CC Date: October 1, 2019 Time: 8:20 am - 5:00 pm