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Recreational fishing is increasingly recognised as an important source of mortality for marine fish populations. In the United States, estimates of marine recreational catch and effort were recently revised for the time period 1981 and beyond, and for many species, the revised estimates were substantially higher than the original values. Here, the proportion of total landings that came from the recreational sector in the Southeast US Atlantic was quantified. The proportions for 22 oceanic species and for all species combined were computed, using a full time series of landings (1981–2016) and a more recent time series (1999–2016). For the full and recent time series, landings of most species (15/22 and 17/22, respectively) were dominated by the recreational sector. For all species combined, 71% of landings in the full time series were from the recreational sector, and 76% in the recent time series. Trend analysis indicated that most species had a stable or increasing proportion of landings from the recreational sector. In addition, stock assessments were conducted on four species, and the catch revisions increased the estimated scale of abundance and, in some cases, affected stock or fishery status. This work underscores the importance of recreational fishing for marine resource management.

Biological reference points (BRPs) are used to determine stock status and set management regulations. While BRPs rely on equilibrium life history data, conditions are not static, and density dependence can play a role. Our objective was to determine the relationship between recruitment strength (i.e., density) and mean length and weight at age for Atlantic Menhaden Brevoortia tyrannus in order to assess the impacts on BRP calculations used for management. Recruitment was tested for autocorrelation and related to time-varying mean lengths and weights at age. Spawning potential ratio (SPR) and yield per recruit (Y/R) benchmarks were calculated across a range of fishing mortality rates, F, and recruitment. Recruitment was autocorrelated and negatively related to mean lengths and weights at age. Both SPR and Y/R were not static under nonequilibrium assumptions about recruitment. To maintain SPR with recruitment increased above equilibrium, F would decrease, while maintaining Y/R would require increase...

The need for “better data” is a common response of stakeholders and managers when confronted with the uncertainty of advice resulting from quantitative stock assessments. Most contemporary stock assessments are based on an integrated analysis of multiple data types, each with their associated cost to collect. Data collection resources are inevitably limited; therefore, it is important to quantify the relative value of increased sampling for alternative data types in terms of improving stock assessments. We approached this universal problem using a simulation study of a hypothetical, amalgam species developed from eight separate stock assessments conducted for species found in southeastern US Atlantic waters. We simulated a population and a stock assessment from the amalgam species and then individually improved alternative data types (indices, age compositions, landings, and discards) by increasing either precision or sample size. We also simulated the effects of increased sampling for alternative groupings of data that might be collected in concert (e.g., commercial, recreational, or survey). Our results show that for the snapper–grouper complex we modeled, age composition data have the largest effect on the accuracy of assessments, with commercial age compositions being the most influential. This is due in part to the relative paucity of age composition data for many southeast US marine stocks, so that modest increases in collection efforts have relatively high benefits for age-based assessment models currently in use for the region. Though this study used data from a particular region of the US, our investigative framework is broadly applicable for quantitatively evaluating the benefits of improved data collection in terms of the precision of stock assessments in any region.

Growth information is important for stock assessments because it gives an indication of spawning stock biomass in the form of weight or fecundity, which is an important indicator of stock status, as well as being important if fitting to length composition data. Sampling for growth characteristics should include all ages and sizes in the population, but data are often only available from fishery-dependent sampling, which can lead to biased estimates of true underlying population growth parameters because of selectivity, which includes both gear selectivity and availability. Two stock assessments with the potential for biased growth because of dome-shaped selectivity and lack of fishery-independent age data are the Gulf and Atlantic menhaden assessments. The objectives of our study were (1) to develop and test a method to estimate unbiased growth parameters regardless of the selectivity of the gear used to sample ages and lengths and (2) to apply the proposed method to fit unbiased population growth parameters for Gulf and Atlantic menhaden. We propose a method to adjust for the bias in the growth curve parameters and account for missing samples at smaller and larger lengths. The proposed method was tested on simulated data and applied to data for Gulf and Atlantic menhaden. Use of the adjustments was robust and resulted in reduced bias in the growth parameter estimates with accuracy being affected by both sample size and variability in mean length at age. Increasing the sample sizes increased the accuracy of the adjustments (i.e., as the coefficient of variation (CV) for length at age increased, the accuracy of the estimates decreased). For Gulf menhaden, the parameters estimated for the unadjusted growth curve were L ∞ = 240.8, k = 0.38, t 0 = −1.14, and CV of length at age = 0.06 (assumed constant) with a total sample size of 366,710 from 1977 to 2011. For Atlantic menhaden, the parameters estimated for the unadjusted growth curve were L ∞ = 350.9, k = 0.32, t 0 = −0.83, and CV of length at age = 0.12 (assumed constant) with a total sample size of 480,668 from 1955 to 2011. The adjustment for a maximum length of capture had a large impact on the overall growth parameters for both species, while the adjustment for a minimum length of capture had less impact. Bias in the growth curve parameter estimates can be reduced by using the method outlined to account for selectivity.

Reliable data on reef fishes inhabiting the southeastern United States (North Carolina to Florida) continental shelf large marine ecosystem are difficult to obtain; catch quotas and time and area closures limit the collection of fishery-dependent samples. Further, unbiased fishery-independent samples are expensive to collect with conventional fishing gear. Consequently, stock assessments are often data-limited, especially for deepwater reef species. We estimated the relative abundance of deepwater reef fish with a double sampling approach using fisheries acoustics and conventional fishing gear (hook and line and chevron traps). Double sampling occurred within the newly-created Snowy Wreck Marine Protected Area and a nearby control site. Reef fish concentrations were identified by a single-beam Simrad ES60 transceiver with a transducer operating at 38 kHz. Hook and line samples were collected at 73 acoustic events, and chevron trap samples were collected at 20 acoustic events. The relationship between fisheries acoustic data and catch-per-unit-effort (CPUE) data was examined to develop a model to predict species-generic CPUE at unfished locations. Akaike's Information Criteria (AIC) found equal support for linear, exponential, and power relationships between acoustic backscatter and CPUE for each conventional fishing gear. Further model development would be aided by refining acoustic target information and applying complimentary fish sampling gears (i.e., split-beam fisheries acoustics gear, underwater video). Given further development, a double sampling design should be useful to estimate the relative abundance of important deepwater reef species over a wide area of the shelf break off the southeastern United States, utilizing either survey vessels or vessels-of-opportunity to rapidly collect acoustic samples.

In modern fishery stock assessments, the productivity of exploited stocks is frequently summarized by a scale-invariant “steepness” parameter. This parameter, which describes the slope of the spawner–recruit curve, determines resilience of a stock to exploitation and is highly influential when estimating maximum sustainable yield. In this study, we examined conditions under which steepness can be estimated reliably. We applied a statistical catch-age model to data that were simulated over a broad range of stock characteristics and exploitation patterns and found that steepness is often estimated at its upper bound regardless of underlying productivity. The ability to estimate steepness reliably was most dependent on the true value of steepness, the exploitation history of the stock, natural mortality, duration of the time series, and quality of an index of abundance; this ability was relatively unaffected by levels of stochasticity in recruitment and sampling intensity of age compositions. We further explored the method of inverse prediction to improve estimates of steepness and conclude that this approach holds promise. We illustrate the utility of simulation and inverse prediction methods with two fish stocks located off the southeastern United States, greater amberjack ( Seriola dumerili ) and gag grouper ( Mycteroperca microlepsis ).

In U.S. federal fishery management, acceptable biological catch (ABC) is set below (or equal to) the overfishing limit to account for scientific uncertainty, and annual catch targets (ACTs) are set below (or equal to) the ABC to account for implementation uncertainty (i.e., imperfect management control). In previous papers, we discussed probabilistic approaches to setting target and limit reference points for fishery management. Here, we explain how those approaches can be adapted to provide ABCs and ACTs over multiple years and otherwise made consist with recent revisions to the National Standards Guidelines, a part of the U.S. Code of Federal Regulations that describes implementation of the Magnuson-Stevens Reauthorization Act. Although described in terms of U.S. fishery management, our methods are sufficiently general for use by researchers in U.S. state agencies or elsewhere in the world. We demonstrate them via an example application to vermilion snapper Rhomboplites aurorubens in U.S. Atlantic waters.

The continental shelf of the southeast United States forms one of North America's Large Marine Ecosystems (LME). Despite increased attention on ecosystem management, fisheries within this LME continue to be managed on a single stock basis, in part because interactions among species and environmental effects are poorly understood. Using fishery data from two different sources (recreational and commercial), we applied multivariate statistical techniques to elucidate spatial and temporal dynamics of reef fish assemblages. Spatial analyses of species composition revealed a zoogeographic boundary near Cape Canaveral, Florida, suggesting that management of reef fishes could be applied to the northern and southern regions with discrimination. Temporal analyses revealed, in general, gradual changes in species composition of landings, but with primary shifts in 1992 and again in 1999–2000. Chronological patterns, evident in these two independent data sets, bear the signature of one or more trending factors, which in this LME could include increased exploitation, spread of invasive species, habitat degradation, or climate change.

Stock assessments indicate many reef fish species have declined in size and abundance in the Atlantic Ocean off the southeastern coast of the United States. However, commercial fishers often state that stock assessments do not match their observations. We compared fishery-independent catch per unit effort (CPUE) and species composition data between the 1970s and 2005-2006 for reef fishes in the vicinity of Onslow Bay, North Carolina. Additionally, total mortality (Z) was estimated by means of a length-based catch-curve analysis. Effort (drops) by rod and reel focused on three sites, two inshore (30 m deep) and one offshore (125 m). The CPUE was compared between periods within each site and larger area (inshore, offshore). The CPUEs of red porgy Pagrus pagrus, vermilion snapper Rhomboplites aurorubens, black sea bass Centropristis striata, and gray triggerfish Balistes capriscus were greater in the 1970s than in 2005-2006 at specific capture sites. Conversely, the CPUEs of red grouper Epinephelus ...

If the Golden Age of fishery modeling is over, the New Industrial Age is beginning. In this new age (the early decades of the 21st century), we1 expect to see increasing use of high-level modeling tools, assessments closely tailored to each stock and its data, more multi-agency collaboration, wider use of multiple-model assessments, and extensive peer review of stock assessments. We hope that fishery management, as well, will be seen as a proper object of peer review, from which it should benefit substantially. We believe that increasing attention will be paid to financial efficiency, both in shaping data collection programs and in specifying what information must be modeled to effect management. If presently depleted stocks start to recover, analysts will be required to examine in more detail the dynamics of increasing stocks. That would constitute a pleasant duty, and one that may yield new insights in population biology.

Because sex is determined by incubation temperatures in sea turtles and immature animals are not sexually dimorphic externally, circulating levels of testosterone measured with radioimmunoassay (RIA), in conjunction with laparoscopies, have been used to estimate sex ratios. From September to December 1995 to 1997, and from June to December 1998 to 2002, we sampled blood from 1106 juvenile loggerhead sea turtles (Caretta caretta) incidentally captured in pound nets set in Core and Pamlico Sounds, North Carolina to measure testosterone levels. Laparoscopies of 89 of these turtles revealed a sex ratio of 2.1F:1M, similar to other juvenile loggerhead populations along the southeastern coast of the USA. Laparoscopies demonstrated that testosterone levels correctly identified males during summer months (water temperatures .23 C), but were unreliable during late autumn/winter months (water temperatures #16 C). During the summer months, females (n 5 201) exhibited testosterone concentrations with an upper limit of 239.0 pg/ml, and males (n 5 69) exhibited a lower limit of 372.0 pg/ml, for a sex ratio of 2.9F:1.0M. We recommend that verification of the RIA should be conducted by laparoscoping a subset of turtles sampled in all sex ratio studies. In addition, this verification should be conducted at several different times throughout the year to evaluate any possible seasonal effects on testosterone concentrations.

Minimum size limits may be ineffective for reef fishes because they often sustain barotrauma when caught from deep (>20 m) waters. A study was undertaken in conjunction with hook-and-line commercial fishermen to calculate discard percentages and evaluate potential release mortality of eight economically important species: black sea bass, Centropristis striata (Linnaeus), red grouper, Epinephelus morio (Valenciennes), snowy grouper, Epinephelus niveatus (Valenciennes), gag, Mycteroperca microlepis (Goode and Bean), scamp, Mycte- roperca phenax (Jordan and Swain), vermilion snapper, Rhomboplites aurorubens (Cuvier), white grunt, Haemulon plumieri (Lacepede) and red porgy, Pagrus pagrus (Linnaeus). Fishing with baited hook and line occurred in 2004 and 2005 in Onslow Bay, NC, in waters 19-150 m deep. Sub-legal discard rates were 15% for vermilion snapper, 25% for red porgy, 7% for red grouper, 33% for gag, 35% for scamp and 12% for black sea bass. Although mortality based on post-release behaviour was relatively low, higher mortalities estimated from models incor- porating hooking location and depth of capture suggest that minimum size limits may not provide the population benefits intended by management in the North Carolina reef fishery.

Sea surface temperature imagery, ship-based surveys, and moored current meters described the passage of a Tortugas Eddy as it moved east at ca. 6 km day -1 through the southern Straits of Florida (SSF). In mid-April 1999 the eddy SST signature extended across half the width of the Straits. While in the western SSF, the eddy center was ca. 30 km seaward of the outer reef. The upper pycnocline, the subsurface chlorophyll a maximum (SCM), and nutricline shoaled from ca. 80 m at the eddy edge to < 60 m at the center. Maximum chlorophyll a concentrations in the SCM were highest near the eddy center, at 1 mg m -3 , although the depth-integrated concentrations (mg m -2 ) were similar across the feature. Nutrient-density relationships show nitrate + nitrite, phosphate, and silicate decreased to detection limits at σ t < 25.0; the SCM was centered near this isopycnal surface. As the Eddy passed Looe Key (81.5W) the alongshore currents reversed to the west. During this period high-nutrient, cool waters shoaled near the bottom on the outer reef. By early May, the eddy SST signature was compressed into a thin band of cool surface waters off the Middle to Upper Keys. As the feature moved towards shore in the Middle to Upper Florida Keys, the nitrate + nitrite and chlorophyll concentrations increased in bottom waters along the outer reef. Processes such as internal tidal bores and breaking internal waves are likely responsible for delivering nutrients from Tortugas Eddies to the outer reef in the Middle to Upper Keys.

Fish harvest policies typically rely on biological reference points for measures of a stock's status. We examine three common biological reference points based on fishing mortality rates corresponding to maximum sustainable yield with an age-structured deterministic model. We incorporate invariant life-history relationships into the model to maintain parsimony and focus model parameters on biologically plausible parameter space. A wide range of biological and fishery characteristics were used in the model so that our results pertain to the management of virtually any exploited population. Results indicate that two biological reference points based on spawning biomass are insensitive to life-history parameters, whereas one based on natural mortality is highly sensitive. All three depend largely on the choice of a stock–recruitment function and on steepness, a measure of the population growth rate. For each of the three, values have been previously proposed that were intended to safely apply to all fisheries; our results show that no such universal values exist. We recommend determining stock–recruitment functions a priori, establishing biological reference points on steepness explicitly and eliminating harvest policies based on the natural mortality rate altogether.

Parameter estimation for the logistic (Schaefer) production model commonly uses an observation-error estimator, here termed the NM estimator, combining nonlinear-function minimization and forward projection of estimated population state. Although the NM estimator can be used to fit the generalized (Pella–Tomlinson) production model, an equilibrium approximation method (EA) is often used, despite calls in the literature to abandon equilibrium estimators. We examined relative merits of NM and EA estimators for the generalized model by fitting 48 000 simulated data sets describing five basic stock trajectories and widely varying population characteristics. Simulated populations followed the generalized production model exactly but were observed with random error. Both estimators were used on each data set to estimate several quantities of management interest. The estimates from NM were usually more accurate and precise than EA estimates, and overall, NM outperformed EA. This is the most comprehensive study of the question to date—the first to examine the generalized production model—and it demonstrates clearly why equilibrium estimators should be abandoned. Although valuable when introduced, they are no longer computationally necessary, they are no less demanding of data, and their performance is poor.

The amount of exploitation in a fishery is typically controlled by regulatory harvest policies, of which the best for maximizing total yield is F MSY, the fishing rate that provides the maximum sustainable yield. However, estimation of F MSY can be difficult for many fisheries, and for this reason proxies such as the spawning-biomass-per-recruit rate (often denoted F %) have been adopted for some fisheries. Around 1992, the Pacific Fishery Management Council adopted an F 35% harvest policy for U.S. West Coast groundfish. Recently, this policy has been questioned, along with the overall productivity of West Coast groundfish. Estimates of appropriate harvest rates and productivity are computed from stock assessment models, which often rely on poorly estimated values for natural mortality and at-sea discard levels. The effects of unaccounted discards and misspecified natural mortality on estimates of appropriate harvest rates were investigated using a basic catch-age model. A deterministic, generali...

Previous studies have shown that Pacific herring populations in the Bering Sea and north-east Pacific Ocean can be grouped based on similar recruitment time series. The scale of these groups suggests large-scale influence on recruitment fluctuations from the environment. Recruitment time series from 14 populations were analysed to determine links to various environmental variables and to develop recruitment forecasting models using a Ricker-type environmentally dependent spawner–recruit model. The environmental variables used for this investigation included monthly time series of the following: southern oscillation index, North Pacific pressure index, sea surface temperatures, air temperatures, coastal upwelling indices, Bering Sea wind, Bering Sea ice cover, and Bering Sea bottom temperatures. Exploratory correlation analysis was used for focusing the time period examined for each environmental variable. Candidate models for forecasting herring recruitment were selected by the ordinary and recent cross-validation prediction errors. Results indicated that forecasting models using air and sea surface temperature data lagged to the year of spawning generally produced the best forecasting models. Multiple environmental variables showed marked improvements in prediction over single-environmental-variable models.

We examined recruitment and average weight-at-age time series for Pacific herring (Clupea pallasi) populations from the Bering Sea and north-east Pacific Ocean to determine similarities. Statistical correlation and multivariate clustering methods indicated Pacific herring populations form large-scale groups. Large year classes occur synchronously among several Pacific herring populations. Multivariate cluster analyses of recruitment and weight-at-age data indicated that Bering Sea herring populations are distinct from north-east Pacific Ocean populations. Within the NE Pacific Ocean, there appear to be three groups of herring populations: a British Columbia group, a south-east Alaska coastal group, and an outer Gulf of Alaska group. Jackknife and randomization tests indicate these groups are robust and not the result of random chance. Deviations from observed herring population groups were examined for indications of anthropogenic perturbations. The Prince William Sound herring populations did not show any strong deviations corresponding to the oil spill of 1989. There might not yet be enough data since the spill to detect changes in the recruitment or weight-at-age data since that time, particularly if oil spill effects were concentrated on the early life history stages.