Recruitment Overfishing Research Articles

Evaluation of population decline and fishing sustainability of the endangered Australian freshwater fish Macquaria australasica

Abstract Macquarie perch, Macquaria australasica Cuvier, is an endangered Australian freshwater fish that has historically supported popular recreational fisheries, but since the 1980s, it has experienced a decline in both distribution and abundance. This study investigated whether a marked decline in the population size of Macquarie perch has occurred at Lake Dartmouth between the mid‐1980s and 2000 and the likelihood of the current legal minimum length (LML) of 350 mm TL protecting the population from recruitment overfishing. Recreational angler survey data showed strong evidence for a temporal population decline. Sampling of the population and construction of a simulation model indicated that the current LML would protect the population from recruitment overfishing. This study highlights the value of specifically investigating suspected threats to endangered fish populations to allow the instigation of effective fisheries management.

Ecologically and evolutionarily sustainable fishing of the pikeperch Sander lucioperca: Lake Oulujärvi as an example

Due to the multitude of participants and a diverse range of fishing gear used freshwater fisheries are often managed using minimum size limits (MSL) rather than regulations of total fishing effort. However, a concern has arisen whether attempts to improve ecological sustainability of fisheries by increasing MSLs would induce undesired adaptations to selective fishing. We examined the ecological and evolutionary impacts of varying fishing mortality rates under varying MSLs, with and without stockings, in an age-, size-, and maturity-structured evolutionary model which was parameterized for the Lake Oulujärvi pikeperch, Sander lucioperca. We found that at the current level of harvesting (fishing mortality rate, F = 0.7) and stockings (430 000 year −1), and under the assumption of strongly density-dependent growth, the nation-wide MSL of 370 mm maximizes theoretical biomass yield in a deterministic model but does not prevent severe recruitment overfishing under further increased fishing pressures or stochasticity in recruitment success. The recently imposed, local MSL of 450 mm better ensures stable yields, and even increases them if individual growth is density-independent, but further increase of MSL to 500 mm would already reduce yield especially if there was discard mortality for undersized fish. Given density-dependent growth, equal survival between wild and stocked fish, and sustainable fishing mortality rate, stockings do not increase yield or significantly improve the stability of yields. Evolutionarily stable size at maturation decreases under strong fishing mortality, but increased MSLs reduce the magnitude of this undesired effect. Negatively size-dependent natural mortality was found to have a positive effect on the otherwise negative selection for length-at-age. Increased MSLs also reduce the total selection for decreased length-at-age. Our results support the intentions to increase MSLs in order to improve both ecological and evolutionary sustainability of recreational fisheries.

Demographic parameters and status assessments of Lutjanus ehrenbergii, Lethrinus lentjan, Plectorhinchus sordidus and Rhabdosargus sarba in the southern Arabian Gulf

Demographic parameters and status assessments for L. ehrenbergii, L. lentjan, P. sordidus and R. sarba in the southern Arabian Gulf were established using a combination of size frequency, biological and size-at-age data. Defined structural increments consisting of alternating translucent and opaque bands in transverse sections of sagittal otoliths were validated as annuli. The maximum age estimates ranged from 5 years for R. sarba to 14 years for P. sordidus. Growth trajectories were significantly different between sexes for L. ehrenbergii and L. lentjan with females achieving a larger asymptotic size than males. Estimates of fishing mortality rates were less than the target (FSB40) and limit (FSB30) biological reference points for L. ehrenbergii, L. lentjan and P. sordidus indicating that these species were exploited within sustainable limits. Conversely, R. sarba was found to be heavily overexploited and recruitment overfishing may have occurred as the fishing mortality rate was considerably greater than the limit reference point and the relative spawner biomass per recruit was 6.4% of the theoretical unexploited level. Due to restrictions in the available data set, the presented results require confirmation from specific studies on natural mortalities and from growth estimates based on more extended size spectra, avoiding any size selective sampling method.

Evaluating the Potential Efficacy of Invasive Lionfish (Pterois volitans) Removals

The lionfish, Pterois volitans (Linnaeus) and Pterois miles (Bennett), invasion of the Western Atlantic Ocean, Caribbean Sea and Gulf of Mexico has the potential to alter aquatic communities and represents a legitimate ecological concern. Several local removal programs have been initiated to control this invasion, but it is not known whether removal efforts can substantially reduce lionfish numbers to ameliorate these concerns. We used an age-structured population model to evaluate the potential efficacy of lionfish removal programs and identified critical data gaps for future studies. We used high and low estimates for uncertain parameters including: length at 50% vulnerability to harvest (Lvul), instantaneous natural mortality (M), and the Goodyear compensation ratio (CR). The model predicted an annual exploitation rate between 35 and 65% would be required to cause recruitment overfishing on lionfish populations for our baseline parameter estimates for M and CR (0.5 and 15). Lionfish quickly recovered from high removal rates, reaching 90% of unfished biomass six years after a 50-year simulated removal program. Quantifying lionfish natural mortality and the size-selective vulnerability to harvest are the most important knowledge gaps for future research. We suggest complete eradication of lionfish through fishing is unlikely, and substantial reduction of adult abundance will require a long-term commitment and may be feasible only in small, localized areas where annual exploitation can be intense over multiple consecutive years.

Simulated Population Responses of Common Carp to Commercial Exploitation

AbstractCommon carp Cyprinus carpio is a widespread invasive species that can become highly abundant and have deleterious ecosystem effects. Thus, aquatic resource managers are interested in controlling common carp populations, but control is difficult, in part, because of the inherent uncertainty as to how populations respond to exploitation. To better understand this response, we evaluated the population dynamics (recruitment, growth, and mortality) of common carp in three natural lakes in eastern South Dakota. Common carp exhibited similar population dynamics across these three systems, which were characterized by consistent recruitment (ages 3–15 being present), fast growth (K = 0.37–0.59), and low mortality (A = 1–7%). We then modeled the effects of commercial exploitation on size structure, abundance, and egg production to determine its utility as a management tool to control populations. All three populations responded similarly to exploitation simulations in which a 575‐mm length restriction represented commercial gear selectivity. Simulated common carp size structure declined modestly (9–37%) in all simulations. The abundance of common carp declined dramatically (28–56% of starting levels) at low levels of exploitation (0–20%), but exploitation greater than 40% had little additive effect, the final populations only being reduced 49–79% despite high exploitation (>90%). At a moderate level of exploitation (40%), maximum lifetime egg production was reduced to 77–89% of starting levels, indicating the potential for recruitment overfishing. Exploitation further reduced common carp size structure, abundance, and egg production when simulations were not size selective. Our results provide insights into the ways in which common carp populations may respond to exploitation. Although commercial exploitation may be able to partially control populations, an integrated removal approach that removes all sizes of common carp has a greater chance of controlling population abundance and reducing the perturbations induced by this invasive species.Received July 23, 2010; accepted January 6, 2011

An Evaluation of the Management Effectiveness of a Stock Re-Building Strategy for a Multi-Species Demersal Trap Fishery in Abu Dhabi, United Arab Emirates

The off-shore demersal trap fishery in the southern Arabian Gulf has been managed by gear regulations and effort constraints which were aimed at rebuilding depleted stocks. In order to evaluate the success of these regulations, a variety of selectivity and other fishery metrics were compared for the key species (Diagramma pictum, Epinephelus coioides and Lethrinus nebulosus) before and after their introduction. With the exception of a minor increase in the mean age at first capture from 1.3 yrs to 1.9 yrs for E. coioides, there were no significant changes in the values or trends in juvenile retention, mean size or the mean sizes and ages at first capture. The comparison of selectivity ogives with data derived independently through an experimental fishing program indicated that the failure of juvenile escape panels to modify the selectivity characteristics of the fishery could not be attributed to a lack of compliance. Furthermore, there were no significant changes in fishing mortality rates, harvest rates, catch, effort, yield per recruit and relative spawner biomass per recruit following the introduction of the management regulations. Age structures were highly truncated and the management measures had failed to increase the relative proportion of older age classes. Stock status indicators suggested that all species were heavily over-exploited with evidence of both growth and recruitment over-fishing. Given the failure of existing regulations to modify gear selectivity, reduce effort and rebuild stocks, the results of the study suggest that management authorities should consider alternative measures including a moratorium on the use of traps in the off-shore demersal fishery of Abu Dhabi.

Exploitation of walleye in a Great Plains reservoir: harvest patterns and management scenarios

Abstract This study assessed exploitation and evaluated management options for walleye, Sander vitreus (Mitchill), in Glen Elder Reservoir, Kansas. A total of 2429 walleye varying from 240 to 687 mm was tagged with Carlin dangler tags during 2000–2003. After correcting for tag loss and non‐reporting, exploitation of walleye was estimated as 68.3%. More than 85% of the tagged walleye were harvested during April to June and 75% were harvested within 6 months after tagging. A Beverton‐Holt yield‐per‐recruit model was used to evaluate six minimum length limits varying from 250 to 610 mm. Given current exploitation rates, population demographics and harvest regulations (381‐mm minimum length limit), the walleye population is probably experiencing recruitment overfishing. Model results suggested that a 610‐mm minimum length limit would be required to prevent growth overfishing and a 533‐mm or longer minimum length limit would prevent recruitment overfishing.

Dependence of recruitment on parent stock of the spiny lobster, Panulirus argus, in Florida

AbstractDespite management practices to achieve sustainability, commercial landings for Florida spiny lobster (Panulirus argus) have experienced a drastic decline (57%) since 2000. This is cause for concern not only for economic reasons, but for issues of sustainability. An annual index of P. argus post‐larval (puerulus) abundance, estimated with a generalized linear model with significant mean sea‐level effects, shows a 36% decrease in annual puerulus supply since 1988. In addition, local Florida spawning stock biomass estimated from an age‐structured sequential population analysis decreased 57% since 1988. Puerulus abundance follows a highly correlated (R = 0.76) trend with a 12‐month delayed spawning stock abundance, which supports the contention that the Florida spawning population is a significant contributing factor to post‐larval recruitment in Florida. Residuals about the puerulus on spawning stock abundance function follow closely an interannual North Atlantic Oscillation Index signal. This residual effect is thought of as a secondary regional population effect on Florida puerulus recruitment. The Florida spiny lobster stock is exploited with no fishing mortality controls due to the Pan Caribbean recruitment concept adopted in Florida spiny lobster management. Therefore, the potential of recruitment overfishing exists if fishing mortality controls to protect local spawning stock abundance, such as catch quotas, are not introduced.

The sharks of South East Asia – unknown, unmonitored and unmanaged

AbstractSharks fisheries have declined globally due to over‐ and unregulated fishing. As with many collapsed and unmonitored coastal fisheries, information is difficult to obtain, yet it is important to understand the historical changes determining population trends and evaluate the current status of sharks in order to conserve these vulnerable species. Here, we document for the first time the history and general condition of the shark fisheries of Southern China, specifically Hong Kong, and Guangdong, Fujian and Hainan Provinces. This study shows, through the use of historical literature and anecdotal accounts, including fisher interviews, that all known shark fisheries in the region collapsed between the 1970s and the 1990s. Of the 109 species present historically in the South China Sea, only 18 species were recorded in current market surveys, of which all were landed as bycatch and 65% were below the size of sexual maturity. Markets are dominated by smaller species, including the spadenose shark (Scoliodon laticaudus) and the whitespotted bambooshark (Chiloscyllium plagiosum). Marketed large shark species are almost all below the size of sexual maturation, evidence of growth overfishing and a factor in recruitment overfishing. Some species, like the whale (Rhincodon typus) and basking sharks (Cetorhinus maximus), are clearly vulnerable to local extinction without intervention. Given the inherent vulnerability of sharks and the overfished states of many sharks, there is clearly an urgent need to formulate impacting conservation and management plans for these rapidly declining species in a region that has the highest demand for shark products globally.

Evaluation of the Japanese eel fishery in the lower reaches of the Kao-Ping River, southwestern Taiwan using a per-recruit analysis

Yield-per-recruit (YPR) and spawning stock biomass-per-recruit (SPR) models were used to investigate the impact of fisheries on the yellow and silver eels of the local stock of Japanese eel ( Anguilla japonica) in the Kao-Ping River (southwestern Taiwan). The current fishery status and uncertainty of biological reference points (e.g., F max, F 0.1, F 40%, and F 50%) were assessed using Monte Carlo simulation. Probabilities of the current fishing mortality rate for yellow and silver eels ( F cur) being higher than F max ranged 15–20%, and being higher than F 0.1 ranged 58–66%. The probabilities of F cur being higher than F 40% and F 50% ranged 26–93% and 73–99%, respectively. The Japanese eel in the lower reaches of the Kao-Ping River appeared to be fully exploited in terms of YPR. This local stock is also subject to a high risk of recruitment overfishing because the contribution of the SPR of the local stock to the entire Japanese eel stock is possibly below a minimal acceptable level (40%). Estimates of F 0.1 and F max, and to a lesser extent those of F 40% and F 50%, were relatively robust, but estimates of the maximal YPR and SPR at F cur were highly sensitive to the uncertainty of the input parameters.

Model averaging and probable status of North Pacific striped marlin, Tetrapturus audax

We show how model averaging can be applied to estimate the probable status of a fishery resource under assessment scenario uncertainty. This approach is applied to North Pacific striped marlin ( Tetrapturus audax ), an apex predator that may be vulnerable to recruitment overfishing in pelagic longline fisheries targeting tunas. In the current striped marlin assessment, two assessment scenarios were used to account for different hypotheses about the steepness of the stock–recruitment dynamics. Estimates of spawning stock and recruitment from these scenarios are used post hoc to fit age-structured production models that represent alternative hypotheses about the degree of compensation in stock–recruitment dynamics and the degree of serial correlation of environmental forcing. Model-averaged estimates of target spawning biomass to produce maximum sustainable yield (SMSY) and the associated limit fishing mortality (FMSY) characterize relative stock status (S/SMSY and F/FMSY) under each scenario. Scenario-weighted averages of relative status determine probable stock status, with weightings reflecting the credibility of each scenario. Estimates of the variance of probable status account for both model selection and assessment scenario uncertainty in risk analyses. Using model averaging to estimate probable stock status from multiple assessment scenarios is analogous to using ensemble averages from multiple predictive models to make weather forecasts.

Age-based life history parameters and status assessments of by-catch species (Lethrinus borbonicus, Lethrinus microdon, Pomacanthus maculosus and Scolopsis taeniatus) in the southern Arabian Gulf

Summary Life history and demographic parameters for Lethrinus borbonicus, Lethrinus microdon, Pomacanthus maculosus and Scolopsis taeniatus in the southern Arabian Gulf were estimated using a combination of size frequency, biological and size-at-age data. Defined structural increments consisting of alternating translucent and opaque bands in transverse sections of sagittal otoliths were validated as annuli. The maximum age estimates ranged from 5 years for Scolopsis taeniatus to 36 years for Pomacanthus maculosus. The size-at-age relationships were highly asymptotic in form with the majority of growth being achieved early in life. There were significant differences in the growth characteristics between sexes for Pomacanthus maculosus, with males approaching a larger asymptotic size at a faster rate than females. With the exception of Scolopsis taeniatus, the mean age at which fish became vulnerable to capture was lower than the mean age at first sexual maturity. The stocks of L. microdon, P. maculosus and S. taeniatus were exploited within sustainable limits, conversely, L. borbonicus was found to be overexploited and recruitment overfishing may have occurred as the relative spawner biomass per recruit was below 30% of the unexploited state.

Stock assessment and efficacy of size limits on longtail tuna ( Thunnus tonggol) caught in Australian waters

A stock assessment of longtail tuna ( Thunnus tonggol) in Australian waters was undertaken using per-recruit analyses to assess: (i) the current stock status, and (ii) the effect of Minimum Legal Lengths (MLL) as a management tool. Exploited age compositions differed between the commercial (age classes 3–4 years) and sport fishery (4–6 years). The fishing mortality ( F current) from these fisheries for 2004–2006 was estimated as 0.167–0.320 year −1. Yield-per-recruit analyses revealed that size limits and improving post-release survival had no significant effect on the population. This was due to fish becoming vulnerable to both fisheries at age 2–3 years, after fish presumably had the opportunity to spawn. Under all MLL scenarios, the current fishing mortality rate did not exceed biological reference points. However, any significant increase in fishing mortality may result in recruitment overfishing due to longtail tuna being slow-growing and the stock currently in the vicinity of the F 40% reference point. Since longtail tuna are now a “recreational-only” species in Australia with minimal commercial bycatch, investigation of daily catch limits for the sport fishery requires exploration using more sophisticated age-structured stock assessment models.

Impacts of Commercial Gill‐Net Bycatch and Recreational Fishing on a Florida Black Crappie Population

AbstractCommercial bycatch can potentially induce high fishing mortality and represents serious concerns for the sustainability of some fisheries. We evaluated the potential population‐level impacts of commercial gill‐net bycatch and recreational fishing mortality on black crappie Pomoxis nigromaculatus in Lake Dora, Florida. We assessed total black crappie bycatch and the mortality rates of black crappie entangled in gill nets, quantified recreational fishing effort and harvest, and estimated exploitation for the recreational and commercial (bycatch) fisheries. We used an equilibrium age‐structured population model to assess potential population‐level impacts of bycatch and recreational fishing mortality. Onboard observer data of commercial fishers showed that about 17,000 and 30,000 black crappie were captured in gill nets in 2005 and 2006, respectively. Cage experiments revealed that about 30% and 47% of black crappie captured in gill nets experienced mortality after 72 h in 2005 and 2006, respectively. The recreational fishery exploitation rate was estimated to be 42% based on angler tag returns in 2006, and commercial exploitation via bycatch from commercial gill nets was 15%. The population model suggested that the level of recreational fishing mortality observed in 2006 was probably sustainable but that additional commercial or recreational exploitation would create a risk of recruitment overfishing. The greatest risk for recruitment overfishing via bycatch occurs when other sources of exploitation are also high (e.g., via a recreational fishery).

Reproductive biology of middle Mississippi River shovelnose sturgeon: insights from seasonal and age variation in plasma sex steroid and calcium concentrations

Shovelnose sturgeon Scaphirhynchus platorynchus are endemic to the Mississippi River drainage and are commercially harvested for roe in several states. The status of shovelnose sturgeon populations throughout much of its range is unknown or declining; Mississippi River stocks are experiencing recruitment overfishing and may be at risk of collapse. Restoration of shovelnose sturgeon populations will require additional information on their reproductive biology, including age at maturity and reproductive status and cycles. The objectives of this study were to determine the effects of reproductive stage, fish age, and season on plasma 17-β estradiol (E2) and calcium (Ca2+) concentrations in female shovelnose sturgeon and plasma testosterone (T) concentrations in male shovelnose sturgeon from the middle Mississippi River (MMR). The relationship was also assessed between plasma vitellogenin (VTG) and Ca2+concentrations for female shovelnose sturgeon. Plasma E2 and Ca2+concentrations in females and T concentrations in males differed among reproductive stages, consistent with results of prior research on shovelnose sturgeon and other sturgeon species. VTG and Ca2+concentrations were strongly correlated in female shovelnose sturgeon, indicating that Ca2+can be used as a surrogate for VTG assays for identification of vitellogenic females, as has been shown for other sturgeon species. Age at maturity was estimated at 10 years for males and 9 years for females based on T and E2 profiles, consistent with other recent age at maturity estimates in the MMR and Wabash River determined by gonadal examination. Peaks in plasma sex steroid and Ca2+concentrations during April and October possibly reflected the spring spawning season and provide additional evidence in support of recent documentation of autumn spawning by shovelnose sturgeon in the MMR. Additional research is needed to elucidate autumn spawning by shovelnose sturgeon in the MMR.

Herring and ICES: a historical sketch of a few ideas and their linkages

Abstract Sinclair, M. 2009. Herring and ICES: a historical sketch of a few ideas and their linkages. – ICES Journal of Marine Science, 66: 1652–1661. This introduction to the Symposium on “Linking Herring” sketches the development of some ideas generated from herring research within an ICES context. The work of Committee A (1902–1908), under the leadership of Johan Hjort, led to a paradigm shift from “migration thinking” to “population thinking” as the interpretation of fluctuations in herring landings. From the 1920s to the 1950s, the focus on forecasting services for the herring fisheries, although ultimately unsuccessful, had the unintended consequence of generating ideas on recruitment overfishing and the match–mismatch hypothesis. The collapse of the East Anglian fishery led, in 1956, to considerable debate on its causes, but no consensus was reached. Three consecutive symposia dealing with herring (1961, 1968, and 1970) reveal a changing perspective on the role of fishing on recruitment dynamics, culminating in Cushing’s 1975 book (“Marine Ecology and Fisheries”, referred to here as the “Grand Synthesis”), which defined the concept of recruitment overfishing and established the future agenda for fisheries oceanography. The 1978 ICES “Symposium on the Assessment and Management of Pelagic Fish Stocks” is interpreted as the “Aberdeen Consensus” (i.e. without effective management, recruitment overfishing is to be expected). In conclusion, herring research within ICES has led to many ideas and two major paradigm shifts.

Population dynamics and potential management of bowfin (Amia calva) in the upper Mississippi River

Summary Bowfin Amia calva are a common species throughout the Mississippi River basin. Although they are generally regarded as a ‘rough’ fish by management agencies and anglers, commercial harvest for their roe has increased in the upper Mississippi River (UMR) basin. Unfortunately, bowfin population dynamics have not received extensive study, resulting in a lack of information that can be used to guide management efforts, particularly in the UMR. The purpose of this study was to investigate the age structure, growth, and reproductive ecology (e.g. age at maturity, fecundity) of bowfin in Pools 11 and 13 of the UMR during the spring of 2007. 118 bowfin from Pool 11 and 138 bowfin from Pool 13 were sampled using modified fyke nets and electrofishing. Size structure, age structure, and growth were similar and sex ratios were near 1:1 in both pools. Female bowfin matured at age 3 and had gonadosomatic index (GSI) values around 9; male bowfin matured at age 2 and had GSI values near 1. Total annual mortality of age-4 and older fish was around 35% for both populations. In both pools, rates of total annual mortality of males were approximately 10% higher than those of females. Growth overfishing occurred in a simulated population with a 500-mm minimum length limit. Recruitment overfishing occurred with 500-mm, 559-mm, and 584-mm limits at moderate to high levels of exploitation; a 635-mm minimum prevented recruitment overfishing at all levels of exploitation.

The roles of fishing and environmental change in the decline of Northwest Atlantic groundfish populations in the early 1990s

The cause of the large decline in groundfish populations in the Northwest Atlantic about 1990 remains unresolved although the prevailing view is that it was due predominantly to fishing. A similar but less extreme decline in these populations that occurred in the early 1970s is also attributed to fishing. However, observational data on commercial fishing effort suggest that fishing effort in the late 1980s was likely less than in the late 1960s–early 1970s, even when efficiency increases are accounted for. Also, the biological changes observed in groundfish populations in the late 1980s were not consistent with a hypothesis that the early 1990s declines in biomass were caused by recruitment overfishing. There is, however, a strong coincidence between fluctuations in groundfish biomass, and other biological characteristics, and variations in the North Atlantic Oscillation (NAO), suggesting that the rapid changes in these characteristics in the early 1990s were largely due to environmental variations, and that this equally may have been true for early 1970s population changes. A corollary to such a hypothesis is that the 1960s, when NAO anomalies were consistently and strongly negative, was a period uniquely favourable for groundfish productivity and should not be taken as a long-term norm.

Effects of Commercial Harvest on Shovelnose Sturgeon Populations in the Upper Mississippi River

AbstractShovelnose sturgeon Scaphirhynchus platorynchus have become an increasingly important commercial species in the upper Mississippi River (UMR) because of the collapse of foreign sturgeon (family Acipenseridae) populations and bans on imported caviar. In response to concerns about the sustainability of the commercial shovelnose sturgeon fishery in the UMR, we undertook this study to describe the demographics of the shovelnose sturgeon population and evaluate the influence of commercial harvest on shovelnose sturgeon populations in the UMR. A total of 1,682 shovelnose sturgeon were collected from eight study pools in 2006 and 2007 (Pools 4, 7, 9, 11, 13, 14, 16, and 18). Shovelnose sturgeon from upstream pools generally had greater lengths, weights, and ages than those from downstream pools. Additionally, mortality estimates were lower in upstream pools (Pools 4, 7, 9, and 11) than in downstream pools (Pools 13, 14, 16, and 18). Linear regression suggested that the slower growth of shovelnose sturgeon is a consequence of commercial harvest in the UMR. Modeling of potential management scenarios suggested that a 685‐mm minimum length limit is necessary to prevent growth and recruitment overfishing of shovelnose sturgeon in the UMR.

Length‐Based Reference Points for Data‐Limited Situations: Applications and Restrictions

AbstractCurrent fisheries management policies generally require an assessment of stock status, which is a difficult task when population and fisheries data are limited. Three simple metrics based on catch length compositions (i.e., that reflect exclusive take of mature individuals,Pmat; that consist primarily of fish of optimal size, the size at which the highest yield from a cohort occurs,Popt; and that demonstrate the conservation of large, mature individuals,Pmega) can be used to monitor population status relative to exploitation. The metrics (collectively referred to asPx) were intended to avoid growth and recruitment overfishing, but there was no quantitative linkage to stock status and calculation of future sustainable catches. We attempt to make this connection by exploring the relationship ofPxmeasures to fishing mortality and spawning biomass (SB). The relationships are compared specifically to the current target reference point (0.4 times the virgin, or unfished, SB [SB0]) and limit reference point (0.25SB0) used for the U.S. West Coast groundfish fishery by using simulations based on a deterministic age‐structured population dynamics model. Sensitivity to fishery selectivity, life history traits, and recruitment compensation (steepness) is explored. EachPxmeasure showed a wide range of possible values depending on fishery selectivity, steepness, and the ratio of the length at maturity (Lmat) to the optimal fishing length (Lopt). Although the values ofPxmay be compatible with sustainable fishing, these values are not always sufficient to ensure stock protection from overfishing. Moreover, values forPxcannot be interpreted adequately without knowledge of the selectivity pattern. A new measure,Pobj(the sum ofPmat,Popt, andPmega), is introduced to distinguish selectivity patterns and construct a decision tree for development of stock status indicators. Heuristic indicator values are presented to demonstrate the utility of this approach. Although several caveats remain, this approach builds on the recommendations of previous literature by giving further guidance related to interpreting catch length composition data under variable fishery conditions without collecting additional information. It also provides a link to developing harvest control rules that inform proactive fisheries management under data‐limited conditions.