National Marine Fisheries Service Research Articles

Geospatial analysis of habitat use by silver hake Merluccius bilinearis in the Gulf of Maine

Three theories of habitat use proposed for marine fishes, the constant density model (CDM), the proportional density model (PDM), and the basin model (BM), make contrasting pre- dictions of how the range, local density, and fitness change as population size changes. We tested model predictions using a survey of silver hake Merluccius bilinearis conducted by the National Marine Fisheries Service every spring and fall. Data on fish length, sex, weight, and reproductive status are collected. Despite a 50% population reduction over the time period of the survey, the geographic area occupied by silver hake did not change significantly. Local density in preferred habitat remained a constant proportion of the entire population. Fitness (as indicated by individ- ual condition) varied over a fine spatial scale, reflected in a pattern of spatial autocorrelation of 10s to 100s of kilometers. Fitness did not exhibit density dependence, except in one case, females in the fall, probably due to the higher energy needs of the females. The results indicate that silver hake conform to the PDM, a site-dependent model, and yet we found some evidence of density dependence in our measure of fitness. Site dependence may work in concert with density depend- ence to regulate population size. Sites silver hake depend on may be the spawning areas along the coast, which may already be in legislatively protected areas. Our study illustrates that an under- standing of habitat use is important for crafting conservation or management measures that lead to maintenance of a stable population.

The use of surrogates in implementation of the federal Endangered Species Act—proposed fixes to a proposed rule

The US Fish and Wildlife Service and National Marine Fisheries Service recently proposed to amend existing regulations that implement the Endangered Species Act’s interagency consultation process by codifying their pre-existing practice of using surrogates to express the amount or extent of incidental take of listed species. The agencies contend that amendments both are necessary as a practical matter and are defensible on ecological grounds. They propose the use of surrogates, either in the form of a substitute species filling in for a species that is challenging to observe or measure, or a land-cover type or another habitat attribute, as proxies for the amount or extent of anticipated take. We contend that the proposed rule leaves the process of surrogate selection and application without essential implementation details and describe five essential steps in surrogate selection and validation. In sum, an obligatory validation procedure should clearly articulate the reasoning behind the selection of the surrogate, including describing the similarities in responses by the surrogate and target species to the same environmental phenomena, linking demographic responses to habitat extent and condition, and describing the uncertainties that accompany the relationship between the status and trends of the surrogate and those of the target species or its habitat under common circumstances.

Killer Whale Depredation and Associated Costs to Alaskan Sablefish, Pacific Halibut and Greenland Turbot Longliners

Killer whale (Orcinus orca) depredation (whales stealing or damaging fish caught on fishing gear) adversely impacts demersal longline fisheries for sablefish (Anoplopoma fimbria), Pacific halibut (Hippoglossus stenolepis) and Greenland turbot (Reinhardtius hippoglossoides) in the Bering Sea, Aleutian Islands and Western Gulf of Alaska. These interactions increase direct costs and opportunity costs associated with catching fish and reduce the profitability of longline fishing in western Alaska. This study synthesizes National Marine Fisheries Service observer data, National Marine Fisheries Service sablefish longline survey and fishermen-collected depredation data to: 1) estimate the frequency of killer whale depredation on longline fisheries in Alaska; 2) estimate depredation-related catch per unit effort reductions; and 3) assess direct costs and opportunity costs incurred by longliners in western Alaska as a result of killer whale interactions. The percentage of commercial fishery sets affected by killer whales was highest in the Bering Sea fisheries for: sablefish (21.4%), Greenland turbot (9.9%), and Pacific halibut (6.9%). Average catch per unit effort reductions on depredated sets ranged from 35.1–69.3% for the observed longline fleet in all three management areas from 1998–2012 (p<0.001). To compensate for depredation, fishermen set additional gear to catch the same amount of fish, and this increased fuel costs by an additional 82% per depredated set (average $433 additional fuel per depredated set). In a separate analysis with six longline vessels in 2011and 2012, killer whale depredation avoidance measures resulted in an average additional cost of $494 per depredated vessel-day for fuel and crew food. Opportunity costs of time lost by fishermen averaged $522 per additional vessel-day on the grounds. This assessment of killer whale depredation costs represents the most extensive economic evaluation of this issue in Alaska to date and will help longline fishermen and managers consider the costs and benefits of depredation avoidance and alternative policy solutions.

Three Decades of U.S. Gulf of Mexico White Shrimp, Litopenaeus setiferus, Commercial Catch Species

Gulf of Mexico, white shrimp, Litopenaeus setiferus, catch statistics have been collected by NOAA’s National Marine Fisheries Service for over 50 years. Recent occurrences such as natural and manmade disasters have raised awareness for the need to publish these types of data. Here we report shrimp data collected from 1984 to 2011. These 28 years of catch history are the time series used in the most recent Gulf of Mexico white shrimp stock assessment. Fishing effort for this stock has fluctuated over the period reported, ranging from 54,675 to 162,952 days fished. Catch averaged 55.7 million pounds per year, increasing significantly over the times series. In addition, catch rates have been increasing in recent years, with CPUE levels ranging from 315 lb/day fished in 2002, to 1,175 lb/ day fished in 2008. The high CPUE’s we have measured is one indication that the stock was not in decline during this time period. Consequently, we believe the decline in effort levels is due purely to economic factors. Current stock assessments are now using these baseline data to provide managers with further insights into the Gulf L. setiferus stocks.

Reproduction of the sandpaper skate, Bathyraja kincaidii (Garman 1908) in the eastern North Pacific

The sandpaper skate, Bathyraja kincaidii, is commonly taken as bycatch in trawl fisheries off central California. The impact of fisheries exploitation on this population is unknown, however little is known about its biology, including its reproductive life history. To determine reproductive aspects of B. kincaidii, 506 individuals were collected from commercial trawls, museum collections, and monthly trawl and longline surveys conducted by the National Marine Fisheries Service. Males ranged from 112 to 635 mm TL, whereas females ranged from 113 to 610 mm TL. Males reach first maturity at 440 mm TL and at ~3 years, whereas females reach first maturity at 450 mm TL, approximately 1 year later. Size and estimated age at 50 % maturity were similar between sexes: 492 mm TL and 7.5 years for males and 467 mm TL and 7.1 years for females. Gonadosomatic index (GSI) and hepatosomatic index (HSI) values indicate a continuous reproductive cycle, with a seasonal peak in the summer and fall, and a resting period following egg case deposition.

A comparison of sampling methods for larvae of medium and large epipelagic fish species during spring SEAMAP ichthyoplankton surveys in the Gulf of Mexico

Annual ichthyoplankton surveys have been conducted in the Gulf of Mexico during spring since 1982 by the National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service (NMFS) Southeast Area Monitoring and Assessment Program (SEAMAP). Historically, ichthyoplankton has been assessed using bongo and surface neuston nets. A new sampling gear, the S‐10 net, was tested between 2009 and 2011. This is a 1 × 2 m frame fitted with a 0.505 mm mesh net, towed in a yo‐yo fashion between the surface and 10 m. Sampling effectiveness of the three gears was compared by examining the abundance and length of larvae of bluefin tuna (Thunnus thynnus) and seven co‐occurring pelagic taxa (Auxis spp., Euthynnus alleteratus, Coryphaena spp., Katsuwonus pelamis, other Thunnus spp., family Istiophoridae, and Xiphias gladius) and vertical distributions of scombrid taxa were examined using MOCNESS samples. Permutational multivariate analysis of variance (PERMANOVA) of net type and time of sampling (day/night) indicated that net type was a significant factor in assessing abundance and length for all taxa. Highest abundances for seven of eight taxa were in S‐10 samples, and MOCNESS samples confirm highest scombrid abundance between the surface and 20 m. Our results show sampling effectiveness strongly depends on the depth fished by the net and that the S‐10 net was more effective than standard SEAMAP bongo and neuston nets. Thus, future sampling with the S‐10 net may improve the annual index of larval abundance for the western population of Atlantic bluefin tuna, traditionally based on abundance from bongo samples.

In search of climate effects on Atlantic Croaker (Micropogonias undulatus) stock off the U.S. Atlantic coast with Bayesian state-space biomass dynamic models

Atlantic Croaker (Micropogonias undulatus) production dynamics along the U.S. Atlantic coast are regulated by fishing and winter water temperature. Stakeholders for this resource have recommended investigating the effects of climate covariates in assessment models. This study used state-space biomass dynamic models without (model 1) and with (model 2) the minimum winter estuarine temperature (MWET) to examine MWET effects on Atlantic Croaker population dynamics during 1972–2008. In model 2, MWET was introduced into the intrinsic rate of population increase (r). For both models, a prior probability distribution (prior) was constructed for r or a scaling parameter (r0); imputs were the fishery removals, and fall biomass indices developed by using data from the Multispecies Bottom Trawl Survey of the Northeast Fisheries Science Center, National Marine Fisheries Service, and the Coastal Trawl Survey of the Southeast Area Monitoring and Assessment Program. Model sensitivity runs incorporated a uniform (0.01,1.5) prior for r or r0 and bycatch data from the shrimp-trawl fishery. All model variants produced similar results and therefore supported the conclusion of low risk of overfishing for the Atlantic Croaker stock in the 2000s. However, the data statistically supported only model 1 and its configuration that included the shrimp-trawl fishery bycatch. The process errors of these models showed slightly positive and significant correlations with MWET, indicating that warmer winters would enhance Atlantic Croaker biomass production. Inconclusive, somewhat conflicting results indicate that biomass dynamic models should not integrate MWET, pending, perhaps, accumulation of longer time series of the variables controlling the production dynamics of Atlantic Croaker, preferably including winter-induced estimates of Atlantic Croaker kills.

Range‐wide movement patterns of Hawaiian monk seals

Marine Mammal ScienceVolume 30, Issue 3 p. 1165-1174 Notes Range-wide movement patterns of Hawaiian monk seals Thea C. Johanos, Corresponding Author Thea C. Johanos Pacific Islands Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1601 Kapiolani Boulevard, Honolulu, Hawaii 96814, U.S.ACorresponding author (e-mail: thea.johanos-kam@noaa.gov).Search for more papers by this authorAlbert L. Harting, Albert L. Harting Harting Biological Consulting, 8898 Sandy Creek Lane, Bozeman, Montana 59715, U.S.ASearch for more papers by this authorTracy A. Wurth, Tracy A. Wurth Joint Institute for Marine and Atmospheric Research, 1000 Pope Road, Honolulu, Hawaii 96822, U.S.ASearch for more papers by this authorJason D. Baker, Jason D. Baker Pacific Islands Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1601 Kapiolani Boulevard, Honolulu, Hawaii 96814, U.S.ASearch for more papers by this author Thea C. Johanos, Corresponding Author Thea C. Johanos Pacific Islands Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1601 Kapiolani Boulevard, Honolulu, Hawaii 96814, U.S.ACorresponding author (e-mail: thea.johanos-kam@noaa.gov).Search for more papers by this authorAlbert L. Harting, Albert L. Harting Harting Biological Consulting, 8898 Sandy Creek Lane, Bozeman, Montana 59715, U.S.ASearch for more papers by this authorTracy A. Wurth, Tracy A. Wurth Joint Institute for Marine and Atmospheric Research, 1000 Pope Road, Honolulu, Hawaii 96822, U.S.ASearch for more papers by this authorJason D. Baker, Jason D. Baker Pacific Islands Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1601 Kapiolani Boulevard, Honolulu, Hawaii 96814, U.S.ASearch for more papers by this author First published: 06 December 2013 https://doi.org/10.1111/mms.12084Citations: 11Read the full textAboutRelatedInformationPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessClose modalShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume30, Issue3July 2014Pages 1165-1174 RelatedInformation

Climate Change, Marine Environments, and the U.S. Endangered Species Act

Climate change is expected to be a top driver of global biodiversity loss in the 21st century. It poses new challenges to conserving and managing imperiled species, particularly in marine and estuarine ecosystems. The use of climate-related science in statutorily driven species management, such as under the U.S. Endangered Species Act (ESA), is in its early stages. This article provides an overview of ESA processes, with emphasis on the mandate to the National Marine Fisheries Service (NMFS) to manage listed marine, estuarine, and anadromous species. Although the ESA is specific to the United States, its requirements are broadly relevant to conservation planning. Under the ESA, species, subspecies, and "distinct population segments" may be listed as either endangered or threatened, and taking of most listed species (harassing, harming, pursuing, wounding, killing, or capturing) is prohibited unless specifically authorized via a case-by-case permit process. Government agencies, in addition to avoiding take, must ensure that actions they fund, authorize, or conduct are not likely to jeopardize a listed species' continued existence or adversely affect designated critical habitat. Decisions for which climate change is likely to be a key factor include: determining whether a species should be listed under the ESA, designating critical habitat areas, developing species recovery plans, and predicting whether effects of proposed human activities will be compatible with ESA-listed species' survival and recovery. Scientific analyses that underlie these critical conservation decisions include risk assessment, long-term recovery planning, defining environmental baselines, predicting distribution, and defining appropriate temporal and spatial scales. Although specific guidance is still evolving, it is clear that the unprecedented changes in global ecosystems brought about by climate change necessitate new information and approaches to conservation of imperiled species. El Cambio Climático, los Ecosistemas Marinos y el Acta Estadunidense de Especies en Peligro.

Chapter 6: The Endangered Species Act

This chapter discusses the Endangered Species Act's role in the United States' legal response to climate change. For readers who are not already familiar with the statute, it begins with an overview of the ESA. The bulk of the chapter then discusses how the Fish and Wildlife Service and the National Marine Fisheries Service — the two administrative agencies primarily responsible for implementing the ESA — and the courts have begun addressing the ESA’s application to climate change.

Interpulse noise assessment during shallow water seismic survey using airgun excitations

Offshore energy exploration and geophysical research activities using seismic airgun arrays are known to generate intense underwater sound. Such seismic imaging has the potential to impact marine mammals through hearing impairment and behavioral modification. Few studies have investigated multipath propagation and reverberation from these airgun impulses. These phenomena could increase the duty cycle within the sound field sufficiently to impact long distance communication or result in detrimental acoustic masking for marine mammals. We report initial findings on the elevation of the sound level between airgun impulses during a shallow, open-water seismic survey. This work uses continuous recordings collected from three bottom-mounted hydrophones deployed in the Beaufort Sea in summer 2012. A quantitative method is used to examine the root-mean-squared noise levels between seismic impulses and the noise level dependence on source range. Preliminary results show that ambient noise increases above non-impulsive harassment levels defined by the National Marine Fisheries Service (120 dB re: 1 microPa) for a portion of the time between seismic impulses at intermediate ranges from the source. In addition, the duration of reverberation is related to the source range, with significantly longer decay times measured on hydrophones at greater distances from the source.

Habitat and diet overlap of 4 piscivorous fishes: variation on the inner continental shelf off New Jersey

1 Marine Field Station Rutgers University 800 c/o 132 Great Bay Boulevard Tuckerton, New Jersey 08087-2004 Present address for contact author: Northeast Fisheries Science Center National Marine Fisheries Service, NOAA 166 Water St. Woods Hole, Massachusetts 02543 2 New Jersey Department of Environmental Protection Nacote Creek Research Station P.O. Box 418 Port Republic, New Jersey 08241 * Deceased

A Framework for Developing Objective and Measurable Recovery Criteria for Threatened and Endangered Species

For species listed under the U.S. Endangered Species Act (ESA), the U.S. Fish and Wildlife Service and National Marine Fisheries Service are tasked with writing recovery plans that include "objective, measurable criteria" that define when a species is no longer at risk of extinction, but neither the act itself nor agency guidelines provide an explicit definition of objective, measurable criteria. Past reviews of recovery plans, including one published in 2012, show that many criteria lack quantitative metrics with clear biological rationale and are not meeting the measureable and objective mandate. I reviewed how objective, measureable criteria have been defined implicitly and explicitly in peer-reviewed literature, the ESA, other U.S. statutes, and legal decisions. Based on a synthesis of these sources, I propose the following 6 standards be used as minimum requirements for objective, measurable criteria: contain a quantitative threshold with calculable units, stipulate a timeframe over which they must be met, explicitly define the spatial extent or population to which they apply, specify a sampling procedure that includes sample size, specify a statistical significance level, and include justification by providing scientific evidence that the criteria define a species whose extinction risk has been reduced to the desired level. To meet these 6 standards, I suggest that recovery plans be explicitly guided by and organized around a population viability modeling framework even if data or agency resources are too limited to complete a viability model. When data and resources are available, recovery criteria can be developed from the population viability model results, but when data and resources are insufficient for model implementation, extinction risk thresholds can be used as criteria. A recovery-planning approach centered on viability modeling will also yield appropriately focused data-acquisition and monitoring plans and will facilitate a seamless transition from recovery planning to delisting.

A revised estimate of daily ration in the tiger shark with implication for assessing ecosystem impacts of apex predators

NOAA, National Marine Fisheries Service, Southeast FisheriesScience Center, 3500 Delwood Beach Road, Panama City, Florida 32408, USAApex predators may impact ecosystem structure and func-tion through trophic cascades (Estes, Tinker & Williams1998). Studies of diets, feeding patterns and food webdynamics can contribute to an understanding of commu-nity structure and ecological interactions (Winemiller 1989;Krebs 1998). Thus, understanding trophodynamics isimportant for developing ecosystem models for predictingcommunity responses to anthropogenic changes (Walters,Christensen & Pauly 1997). Studies of this kind are espe-cially critical in the case of large sharks, given that severalspecies are experiencing varying levels of populationdeclines on a global scale (Dulvy et al. 2008; Camhi et al.2009). Accordingly, there is mounting concern – andincreasing effort – to predict the consequences of largeshark declines for food web dynamics (Estes et al. 2011).In a recent study, Hammerschlag et al. (2012) investi-gated the movement patterns of an apex marine predator,the tiger shark (Galeocerdo cuvier), in relation to an eco-tourism provisioning site. The authors rejected the nullhypothesis that sharks displayed restricted long-term habi-tat use at the site. However, they speculated that theobserved long-term and large-scale shark movements maybe related to cryptic, lesser-understood aspects of Atlantictiger shark life history (i.e. reproduction, mating, foragingforays).As part of their discussion, Hammerschlag et al. (2012)considered the daily ration of 210-kg adult female tigersharks. However, no published studies exist that havequantified this aspect of tiger shark food-consumptiveneeds. To get a broad approximation of daily ration, theauthors averaged values derived from two other species ofsharks found in the subtropical Atlantic: the lemon shark(Negaprion brevirostris), daily ration estimate of 2 1%body weight (Cortes & Gruber 1990); and shortfin makoshark (Isurus oxyrinchus), daily ration estimate of 4 6%body weight (Wood et al. 2009). The species used in thecalculation here were chosen in part because of theirbehavioural and geospatial overlap with the tiger sharkmovements found in Hammerschlag et al. (2012). How-ever, the resulting approximation of the daily ration valuefor an adult tiger shark (3 7%) is likely inflated for twoprimary reasons: (i) using values derived from juvenile spe-cies, although daily ration in sharks is known to decreasewith size (Wetherbee & Cortes 2004) and (ii) averaging val-ues from two species, one of which, the shortfin mako, isregionally endothermic, while tiger sharks are ectothermic(Carlson, Goldman & Lowe 2004).Here we present a different, more traditional approachto estimate the daily ration for tiger sharks followingWinberg (1956). Accordingly, daily ration (kcal day

Analysis of harbor porpoise gillnet bycatch, compliance, and enforcement trends in the US northwestern Atlantic, January 1999 to May 2010

In 1999 the US National Marine Fisheries Service (NMFS) implemented regulations to limit harbor porpoise Phocoena phocoena incidental bycatch in US waters of the northwestern Atlantic. This effort was called the Harbor Porpoise Take Reduction Plan (HPTRP) and included a mixture of time-area closures, pinger and other gear modification requirements, a pinger training program, and outreach and education efforts. This paper focuses on the plan from January 1999 to May 2010 and examines trends in bycatch patterns, compliance with the plan, enforcement of the plan requirements, and changes in the primary fisheries involved in harbor porpoise bycatch. Over the course of the plan harbor porpoise bycatch dropped in the first few years, increased to unacceptable levels during the middle years, and moderated in the later years of the plan. Changes in fishing effort and distribution of key fisheries played a large role in decreasing the bycatch in much of the Mid-Atlantic and also in increasing bycatch in Southern New England and off the coast of New Jersey. The pattern in compliance levels had an inverse relationship with bycatch levels, with better compliance and lower bycatch in early and late years, though compli- ance was generally poor even when at its best. Enforcement of HPTRP regulations was not well documented, but, from available compliance data, it appears that what enforcement did occur was not sufficient to improve compliance. Given poor compliance with pinger requirements, these requirements have not resulted in the expected reduction in bycatch.

Killer whale (Orcinus orca) depredation effects on catch rates of six groundfish species: implications for commercial longline fisheries in Alaska

AbstractPeterson, M. J., Mueter, F., Hanselman, D., Lunsford, C., Matkin, C., and Fearnbach, H. 2013. Killer whale (Orcinus orca) depredation effects on catch rates of six groundfish species: implications for commercial longline fisheries in Alaska. – ICES Journal of Marine Science, 70: 1220–1232. Killer whale (Orcinus orca) depredation occurs when whales damage or remove fish caught on longline gear. This study uses National Marine Fisheries Service longline survey data from 1998–2011 to explore spatial and temporal trends in killer whale depredation and to quantify the effect of killer whale depredation on catches of six groundfish species within three management areas in Alaska: the Bering Sea, Aleutian Islands and Western Gulf of Alaska. When killer whales were present during survey gear retrieval, whales removed an estimated 54–72% of sablefish (Anoplopoma fimbria), 41–84% of arrowtooth flounder (Atheresthes stomias) and 73% (Bering Sea only) of Greenland turbot (Reinhardtius hippoglossoides). Effects on Pacific halibut (Hippoglossus stenolepis) and Pacific cod (Gadus macrocephalus) were significant in the Western Gulf only with 51% and 46% reductions, respectively. Overall catches (depredated and non-depredated sets) for all groundfish species significantly impacted by killer whale depredation were lower by 9–28% (p &lt; 0.05). Effects on shortspine thornyhead (Sebastolobus alascanus) catches were not significant in any management area (p &gt; 0.05). These results provide insight into the potential impacts of killer whale depredation on fish stock abundance indices and commercially important fisheries in Alaska and will inform future research on apex predator–fisheries interactions.

Marine Mammal Monitoring on Guam

Data on marine mammals, specifically information on their stock numbers, seasonal migrations, population structure, habitat use, and behaviors is limited. This study of island associated resident pods of the long nosed spinner dolphin (Stenella longirostris) was conducted near the island of Guam, part of the Mariana Archipelago, south of Japan. These spinner dolphins may be negatively impacted by an increased United States military presence on Guam which leads to expanded training activity, population growth, coastal development and associated tourism. This study compiles historical and current data on marine mammal sightings and behaviors to study possible impact of US military presence. The long nosed spinner dolphins (S. longirostris) are of particular interest because of their proximity to shorelines, their habitat use, and their daily activity schedule. Current data was collected from interviews and sighting events. Standard photo documentation and field survey protocols developed by the National Marine Fisheries Service (NMFS) Pacific Islands Fisheries Science Center (PIFSC) were used. This study created a preliminary marine mammal database for Guam and has expanded the limited information available. In addition, sighting information was used along with geographical information system (GIS) software to combine NOAA benthic habitat maps with multibeam bathymetry to gain a better understanding of the habitats occupied by documented species. Preliminary results suggest that S. longirostris populations in Guam have similar circadian and seasonal rhythms as Hawaiian S. longirostris populations. The results also demonstrate that Guam spinner dolphins show a preference for clear, relatively shallow open water bays with underlying, unconsolidated sediment (sandy bottoms). An increase in military use of shallow bays and dolphin-associated ecotourism could therefore negatively impact resident populations of the Guam spinner dolphins.

Modeling seabird bycatch in the U.S. Atlantic pelagic longline fishery: Fixed year effect versus random year effect

Year is usually modeled as a fixed effect in catch rate analyses because the annual variation is of interest. However, question rises when annual estimates are sensitive to whether modeling year as a random or a fixed effect. With the observer data from the National Marine Fisheries Service Pelagic Observer Program during 1997–2010, we conducted a simulation study using the delta model due to high percentage of zero observations in the observer data. The delta model consisted of two sub-models, one for modeling positive catch data, i.e., the longline sets with at least one seabird caught (positive catch sub-model) and the other for estimating the probability of catching seabirds (probability sub-model). We constructed five scenarios where data contained no year effect, fixed year effect, and random year effect with three increasing randomness, and evaluated the performance of three candidate models in terms of mean absolute error and mean bias. The three candidate models included the delta model where both sub-models had data select year based on its significance, the delta model where both sub-models fixed year in the model regardless of its significance, and the delta model where both sub-models modeled year as a random effect. Results showed that the model with random-year-effect performed the best in all scenarios for analyzing the positive catch data, followed by the one having data select year and the one with year fixed regardless of its significance. For estimating the probability of catching seabirds, performance of the three candidate models were competing in all scenarios except for one scenario where the probability sub-model having data select year performed the best. Combining the two sub-models, the random-year-effect delta model showed superiority over the other two candidate models for estimating seabird bycatch in the longline fishery. We suggest conducting such a simulation study in seabird bycatch assessment, especially in cases where yearly estimates from the random-year-effect and the fixed-year-effect models show great discrepancy.

Spatial and temporal distribution of Atlantic mackerel (Scomber scombrus) along the northeast coast of the United States, 1985–1999

Abstract Radlinski, M. K., Sundermeyer, M. A., Bisagni, J. J., and Cadrin, S. X. 2013. Spatial and temporal distribution of Atlantic mackerel (Scomber scombrus) along the northeast coast of the United States, 1985–1999. – ICES Journal of Marine Science, 70: 1151–1161. The distribution of Atlantic mackerel (Scomber scombrus) during their spring migration along the Mid-Atlantic Bight and into the Gulf of Maine has historically been associated with spring warming along the continental shelf. Variations in mackerel distributions based on National Marine Fisheries Service spring surveys were compared with variations in sea surface temperature (SST) from satellite remote sensing for the eastern US continental shelf for the period 1985–1999. The mackerel stock was first analysed as a unit, then separated into three size classes to assess differences in distribution among years and individuals of various lengths. Results showed an across-shelf correlation between catch and March SST in the Mid-Atlantic Bight for both the entire population and each size class. Along-shelf catch variations were correlated with SST for large mackerel, but not total stock or smaller size classes. Finally, the distribution of mackerel length in the Gulf of Maine was negatively correlated with March SST in the Great South Channel. Results suggest surface temperature along the northeast continental shelf may be used to predict certain, but not all, aspects of annual migration along the shelf, and that factors in addition to temperature are also important in controlling distributions of Atlantic mackerel.

Assessing Efficacy of Non-Lethal Harassment of Double-Crested Cormorants to Improve Atlantic Salmon Smolt Survival

Abstract Salmo salar (Atlantic Salmon) smolts are exposed to predation pressure as they migrate from freshwater into the estuary and near-shore marine environment. In particular, Phalacrocorax auritus (Double-crested Cormorants) are a predator of Atlantic salmon smolts during their estuary and near-shore migration. National Oceanic and Atmospheric Administration's (NOAA) National Marine Fisheries Services’ (NMFS) telemetry data collected prior to this study (1997–2003), suggest that smolts are being removed from the Narraguagus River on their downstream out-migration. This removal may be the result of Cormorant predation. We investigated whether smolt survival could be improved by disrupting normal Cormorant foraging activity by integrating passive smolt tracking and active harassment techniques. Smolt movement and usage of various portions of the estuary according to light condition and tidal stage were explored along with concurrent avian harassment. Although harassment only occurred in approximately 33...