Striper & Fluke Assessment
Rhode Island Saltwater Fishing
The Marine Recreational Information Program (MRIP), formerly the Marine Recreational Fishery Statistics Survey (MRFSS), is a collaborative recreational data collection and estimation program that includes state, regional, and federal partners. Recreational data is collected from anglers and Captains through a suite of surveys, each designed to collect a unique piece of data that is used in the overall estimation of recreational catch and effort. Although the program has seen many improvements over the years, the findings of a 2006 review by the National Research Council prompted MRIP to make improvements to the design of several surveys.
One of the surveys, the Access Point Angler Intercept Survey (APAIS) has trained samplers go into the field at public locations, such as boat ramps and marinas, and interview anglers about the fishing trip they just completed. The sampler has a list of questions that they ask the angler designed to collect information regarding the species harvested and released, as well as the fishing trip itself. In 2013, APAIS implemented an improved survey design to address the potential for bias in survey results. To make the estimates generated under the new sampling design comparable to the pre-2013 estimates, a calibration model was developed. This model passed peer review in 2018 and became available for management use.
Also in 2018, a random-digit-dial telephone survey known as the Coastal Household Telephone Survey (CHTS), was discontinued and a new mail-based Fishing Effort Survey (FES) that began in 2015 was adopted as the source of recreational fishing effort data. The effort survey is used to estimate the number of fishing trips taken by shore and private boat anglers. Both the CHTS and FES were conducted side-by-side for three years (2015-2017) to facilitate the development of a calibration model that would be used to re-estimate historical effort data, similar to what was done for APAIS. The FES calibration model became available for use after it passed peer review in 2017. The APAIS and this effort survey are used in tandem to generate recreational fishing catch and effort information.
Recreational catch and effort estimates are important data sources for any species stock assessment. This data can inform the model about how much recreational fishing pressure a species is under and can characterize the recreational fishery removals from both harvest and releases. The 2018 benchmark stock assessments for striped bass and summer flounder were both peer reviewed in November 2018 at the Northeast Regional SAW/SARC 66 (NEFSC 2019). The benchmark stock assessments for these two species were the first to include the newly calibrated MRIP catch and effort estimates, and provided the first opportunity to look at the effects of the transition to the FES in 2018, and the calibration of historic catch and effort data using the APAIS and FES calibration models.
2018 Benchmark Striped Bass Stock Assessment
The 2018 benchmark striped bass stock assessment used recreational catch estimates from 1982 – 2017 as a source of removals in a statistical catch-at-age (SCA) model. Catch estimates included both direct harvest and live releases. The assessment compared uncalibrated harvest and dead release estimates to estimates that incorporated just the calibrated APAIS, as well as estimates that incorporated both the calibrated APAIS and FES. These comparisons showed that calibrated MRIP estimates were significantly higher than non-calibrated MRIP estimates, and that the incorporation of the FES calibration was largely responsible for the observed difference (Figure 1; NEFSC, 2019). Calibrated harvest estimates were on average 140% higher while calibrated live releases were on average 160% higher. Despite these differences, both the calibrated and non-calibrated estimates showed similar trends in spawning stock biomass (SSB) over time (NEFSC, 2019).
The impact of these data on the assessment findings was also significant. In order for the striped bass population to be able to support the larger recreational removals indicated by the newly calibrated MRIP estimates, the model estimated that there was also a higher level of SSB than previously indicated. Although the 2018 SCA model shows a similar declining trend in female SSB to that of the 2013 SCA model, the decline since 2012 became much sharper. The striped bass population is defined as overfished when the female SSB is below the estimate of female SSB in 1995, the year the striped bass population was declared restored. Female SSB in 2017 was estimated at 68,476 mt, a value below the SSBthreshold of 91,436 mt, indicating the striped bass stock is overfished.
The fishing mortality rate (F) that will maintain the striped stock at the SSBthreshold is the defined as the Fthreshold. In the 2018 SCA model the Fthreshold was estimated to be 0.240 and F in 2017 was estimated to be 0.307, indicating the stock is experiencing overfishing.
While the newly calibrated MRIP estimates are thought to be a major factor contributing to the finding that the striped bass stock is overfished and overfishing is occurring, other contributing factors include the reduced bag limits from Addendum IV and sizeable year classes that have not yet fully recruited to the fishery and are increasing discards in the Chesapeake Bay and along the coast.
At its February 2018 meeting, the striped bass board tasked the Technical Committee (TC) with determining the removals needed to reduce fishing mortality down below the target and threshold levels by 2020. The TC will report back to the Board in May at which time the Board will also discuss the striped bass stock assessment report and peer review reports, and determine if action in response to the assessment findings is necessary.
2018 Benchmark Summer Flounder Stock Assessment
Similar to the striped bass stock assessment, the 2018 benchmark summer flounder stock assessment used recreational catch estimates from 1982 – 2017 as a source of removals in a statistical catch-at-age (SCA) model. Catch estimates included both direct harvest and live releases, but only a portion of the live releases are considered removals (dead). The assessment compared uncalibrated harvest and dead release estimates to estimates that incorporated both the calibrated APAIS and FES. As was the case for striped bass, these comparisons showed that calibrated MRIP estimates were significantly higher than non-calibrated MRIP estimates, with the FES calibration being the main driver of the difference in the new estimates. Calibrated harvest estimates increased total harvest by an average of 29% over the time period analyzed. The differences generally scaled the biomass of the population up, but the trends through time were similar to the old estimates.
The impact of the newly calibrated data on the summer flounder assessment was similar to striped bass with regard to increasing the population size to support the additional removals (Figure 2; NEFSC, 2019). However, in the case of summer flounder, stock status (relative to current reference points) and model diagnostics improved with the new data. One of the big differences between striped bass and summer flounder is in the proportion of the removals that are attributed to the recreational fishery. For striped bass, recreational harvest represents the vast majority of the removals, while for summer flounder, it represents just over half of the removals. This may be one of the factors driving the different outcomes between the two models with regard to how the models reacted to the new calibrated data.
Stock status and working through those issues with striped bass will be the main challenge for that fishery in the coming year. For summer flounder, the challenge will be how to contend with the resource allocation between the recreational and commercial fisheries. As a case in point, the commercial quota will increase significantly in 2019, but recreational regulations will stay close to what they are now due to the fact that the recreational harvest was higher than earlier projections anticipated due to the calibration, while the commercial fishery was constrained to the quota. Deciding how to handle this effect of the recalibration will likely keep fishery managers busy over the coming couple of years.
There are a number of other species scheduled to have their assessments updated in 2019, including some important recreational species such as black sea bass, scup, and bluefish. It remains to be seen how these species assessments may react to the calibrated data. Bluefish is similar to striped bass with regard to it having mostly recreational harvest so may have a significant change. Scup has only a small portion that is recreational so may not change much. Black sea bass is similar to summer flounder with about half of the fishery coming from recreational harvesters, but black sea bass has a fairly complex spatial assessment, therefore the impact is hard to prognosticate. Regardless, the newly calibrated data has consequential implications and the results of this change i n our understanding of the recreational fisheries will continue to play out over the coming years for important recreational species.