Mrc basses 18_jan2012_forweb

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  • Today I will start with a brief background on the three basses in southern California followed by the results of our fishery analysis, management options to consider, and Department recommendations for going forward.
  • During the fishery and management evaluation process, the Department was guided by the Marine Life Management Act. We attempted to obtain the best available science for conducting a thorough fishery analysis and later shared a brief summary of our results with our constituents to obtain their input. The last two policies listed here were considered when we explored different management options and recommendations.
  • Of the three basses, kelp bass range the farthest north and prefer kelp/rock habitat. It is the most historical fishery of the three species, and is targeted along the mainland coast and at the islands.
  • Barred sand bass range less to the north and prefer sand/reef habitat. It has been popular since the 1970s and is primarily a mainland fishery. Barred sand bass are unique from the other two basses in that they form very large spawning aggregations at predictable times and locations, which makes them extremely vulnerable to harvest impacts.
  • Spotted sand bass can be caught as far south as Mazatlan, Mexico, including the Gulf of California. They are caught within bays and harbors, and this fishery didn’t become popular until the 1980s. Approximately 94% of spotted sand bass are caught and released.
  • Here is a figure of the percent of harvested catch by fishing mode. Party/charter modes (in green) comprise a large percent of the total barred sand bass and kelp bass catch, while the private/rental mode comprises the majority of spotted sand bass catch. The basses have been successfully managed under the same bag and size limits for over 50 years: 10 fish in combination, 12-inch minimum size limit. However, in recent years, concerns have been raised regarding the basses, especially for kelp bass and barred sand bass. Spotted sand bass were more recently mentioned in public comment at Commission Meetings; however, our analysis is focused on barred sand bass and kelp bass . . . spotted sand bass will be revisited when we address management options.
  • Growing concerns in recent years have centered around significant catch declines for barred sand bass and kelp bass. These data are commercial passenger fishing vessel landings from 1980 to 2011. As you can see, catch declines for barred sand bass have been more dramatic and have occurred over a shorter period of time. In 2010, the Department initiated an in-depth fishery analysis for both species.
  • Initially, we looked at trends in catch per unit effort because in some instances, CPUE may reflect changes in population abundance. Here we see that although landings for both species showed declines, trends in CPUE were relatively stable over the past 30 years, with the exception of barred sand bass, which shows a dramatic decline after 2004. Unfortunately, catch data alone are inadequate to address the status of these fisheries.
  • This is a graphic presented during Dr. Erisman’s talk in Oct. 2010, and has been slightly modified. Hyperstability is especially relevant to kelp bass and barred sand bass. Due to the aggregating behavior of both species and because their aggregations can be targeted, it is possible that a period of hyperstability in catches can disguise actual trends in the population. This has been demonstrated for many aggregate spawners world-wide. For example, catch per unit effort may remain stable over time even though the actual population size is decreasing. We must look to other indices of abundance to determine whether catches are indeed depressed.
  • Hyperstability can also influence catch ranges. In theory, when fish of an aggregating species are abundant, catch rates are high over a large geographic range, and when the fish are scarce, catch rates remain high only within a smaller geographic range.
  • Today I will start with a brief background on the three basses in southern California followed by the results of our fishery analysis, management options to consider, and Department recommendations for going forward.
  • Today I will start with a brief background on the three basses in southern California followed by the results of our fishery analysis, management options to consider, and Department recommendations for going forward.
  • Today I will start with a brief background on the three basses in southern California followed by the results of our fishery analysis, management options to consider, and Department recommendations for going forward.
  • Today I will start with a brief background on the three basses in southern California followed by the results of our fishery analysis, management options to consider, and Department recommendations for going forward.
  • Today I will start with a brief background on the three basses in southern California followed by the results of our fishery analysis, management options to consider, and Department recommendations for going forward.
  • Today I will start with a brief background on the three basses in southern California followed by the results of our fishery analysis, management options to consider, and Department recommendations for going forward.
  • To examine trends in fish availability over time, we obtained fishery-independent datasets from a variety of organizations. Our goal was to obtain data across all life stages, and today we will be sharing with you representative datasets for each life stage.
  • These graphs represent trends in adult densities of barred sand bass and kelp bass on the mainland. Barred sand bass densities peaked twice; once in 1985 and again in 2000; while kelp bass densities peaked in the early 1980s, declining in the mid 1990s. In both cases, densities in recent years are near or at the same densities observed in the late 1970s.
  • Densities of adult kelp bass at Santa Cruz and Anacapa islands were highest in the 1980s before dropping off in the mid 1990s.
  • Subadult barred sand bass and kelp bass are occasionally sucked into coastal power plant pipes during the power plant cooling process. Barred sand bass and kelp bass abundances were highest in the 1980s and 1990s. Over the last 10 years, subadult abundances have dropped back down to levels observed in the late 1970s.
  • The longest fishery independent data source for the basses is larval abundance data. The rockbasses include all 3 bass species; however these data primarily represent barred sand bass and kelp bass. Rockbass larval abundance peaked in the 1980s and 1990s, with two low periods before and after. So across the three life stages there appears to be a pattern emerging in the abundance data. We believe this pattern is related to changing oceanographic conditions over the last several decades.
  • If we look at the long-term trends in the Pacific Decadal Oscillation, we can see that in the mid-to-late 70s we were just coming out of a cold regime. In the 1980s and 1990s we were in a warm regime, and following 1998, we entered a cooler water period again. The timing of the low periods of adult, subadult, and larval abundance suggests that kelp bass and barred sand bass populations may be responding to changes in oceanic conditions. During warmer water years, the populations appear to do better.
  • For example, when we plot the historical larval abundance time series by oceanographic regime, we do in fact see that larval abundance peaked more frequently during the warm regime than any other period.
  • Historical catches of kelp bass and barred sand bass also appeared to be affected by oceanographic changes. Historically, kelp bass was noted to be the “mainstay” of the fishery, and barred sand bass were considered scarce, especially during cool periods. Beginning in the mid-to-late 70s, barred sand bass became more available and their catches notably increased. You will also notice that prior to the emergence of the barred sand bass fishery, kelp bass catches dramatically declined. Looking further into recreational catch trends during this time period, we discovered a dramatic increase in catches of rockfish, which we know favor cooler ocean temperatures.
  • We also investigated the affect of kelp canopy coverage on kelp bass densities. Several studies have shown a positive relationship between kelp and kelp bass densities at small spatial scales. In this example, we have kelp canopy coverage off San Onofre and numbers of kelp bass entrained by the nearby power plant. Interestingly, temporal trends in kelp bass abundances lag kelp canopy coverage by 2 years, the approximate age of entrained kelp bass. This relationship is important to consider because during warm oceanic regimes, kelp can be destroyed by El Nino conditions and heavy storms. This could partially explain why kelp bass numbers began to decrease in the mid-90s.
  • Next, we looked to length data to gauge relative fishery recruitment strength over time. Because we have a minimum size limit, the most frequently observed age class in any given year should generally be the fishery recruits. The gray area represents the approximate age of fishery recruits. For a period of time after 2005, the dominant age class increased in age in successive years. This indicates that either the fishery suffered from poor fishery recruitment during those years or that those fish represent a very successful year class. Back-calculating, we determined that these fish represent the 1997 year class. If we look at CPFV CPUE during this time period, we see that this period coincides with the dramatic decline in CPUE. Thus, fishery recruitment must have been poor for several years. In effect, we were fishing down the available catch because there were fewer fishery recruits to supplement the fishery.
  • We did the same analysis for kelp bass. And interestingly enough, we observed a similar trend. During the same time period, fishery recruitment was poor and resulted in fishing down the available catch. This indicates to us that population recruitment failure must have occurred several years in a row, specifically, in 1998, 1999, and 2000.
  • The time frame in question is highlighted here in red. Taking a look at the larval abundance data again, we see that larval abundance was extremely low during this period. It is possible that cooler ocean temperatures reduced larval survival. And it is also possible that reduced densities of adult kelp bass during the 1990s contributed to reduced larval abundances.
  • In a separate analysis, we plotted the size structure of harvested catch (fish that are kept). Each colored bar represents a different size class, and potentially, a different age class. Despite fewer numbers of kelp bass and barred sand bass in recent years, the sizes of fish in the harvested catch over the entire 35-yr time period include at least 12 different age classes. Having many different age classes represented in the catch indicates to us that the population has maintained a stable size structure over time. A stable size structure is not characteristic of a collapsed fishery. However, if the depressed populations experience a prolonged period of recruitment failure, we could see dramatic changes in the size structure of the catch.
  • Given the apparent depressed status of each fishery, we have concern for both species; however, the degree of regulatory action, should be dictated by the level of concern for each species. For example, barred sand bass will likely require extra protection because they may be more affected by cooler ocean temperatures and because they form relatively larger, more localized, and more intensely targeted spawning aggregations.
  • All three species of bass are warm temperate species whose populations are susceptible to recruitment failure during cooler oceanic periods. Due to the uncertainty in the actual spawning stock biomass for each species and in what the oceanic conditions will be like in the near future, precautionary management measures appear prudent. Thus, we feel that during these suboptimal environmental conditions, one of our goals should be to mitigate fishing effects in order to favor population rebounds of our basses. We have discussed traditional management options with our constituents, including a reduction in the bag limit and a change in the size limit.
  • We also mentioned providing measures to protect barred sand bass during spawning season in the form of either a seasonal closure or an in-season reduction in the bag limit.
  • Constituent input during our outreach efforts varied widely.
  • This graphic portrays the percent savings under various hypothetical bag limits. Because spotted sand bass are primarily released, we can see that the savings is minimal under various bag limits relative to the other two species. For barred sand bass and kelp bass, percent savings are minimal to modest under hypothetical bag limits of 9, 7, and 5 fish. This is because the vast majority of bags in this analysis contained 5 fish or fewer. If we consider an in-season regulation to reduce the bag limit for barred sand bass to 3 fish, the savings would be approximately 27%. You can see that this provides similar savings to having a year-round 3-fish bag limit.
  • This graphic displays percent savings under various hypothetical minimum size limits. Minimum size limits can provide the highest fishery yield in weight for fisheries. Our current size limit is based on a maximum fishery yield between 12 and 13 inches. In the case of spotted sand bass, we can see that increasing the minimum size limit to 13 inches would provide 40% savings in harvested fish, significantly more savings than a reduction in the bag limit. Increasing the limit to 13 inches provides almost twice the savings for kelp bass as it does for barred sand bass.
  • This graphic displays the percent savings of fish caught during peak spawning season by 2 wk intervals. Peak spawning season is from June to August. A barred sand bass closure during the last two weeks of July would offer the highest percent savings.
  • Bass populations have become depressed in recent years in part due to cooler ocean conditions and fishing. Thus, we feel it important to consider management measures that will favor fishery enhancement.
  • The Department recommends a bag limit reduction and minimum size limit increase for all three basses. A bag limit reduction would provide modest savings, and an increase in the minimum size limit would allow for at least 1 additional year of spawning. In addition, we recommend a partial season closure for barred sand bass to allow for a period of time with uninterrupted spawning activity.
  • After considering the influence of oceanic changes on catches, we feel it will be important going forward to continue to evaluate regulation effectiveness. This should allow for periodic changes to management in order to maximize fishing opportunities for the basses in the future.
  • Mrc basses 18_jan2012_forweb

    1. 1. Fishery Analysis on the Basses in Southern California E.T. Jarvis, H.L. Gliniak, and C.F. Valle Marine Resources Committee Mtg. Santa Barbara, California January 18, 2012
    2. 2. Overview• Background• Summary of fishery analysis• Management options for consideration• Department recommendations Photo: Tom Schabow
    3. 3. Policies for Achieving the Goals of the Marine Life Management Act (MLMA) 1. Science 2. Constituent Involvement 3. Adaptive Management 4. Socio-Economic ConsiderationsPhotos: DFG
    4. 4. Kelp Bass, Paralabrax clathratus• Range: Columbia River, WA/OR border to Magdalena Bay, Baja• Associated with kelp/rocky reef• Popular recreational fishery since 1940s• Mainland and island fishery Photo: Rob Johnson
    5. 5. Barred Sand Bass, Paralabrax nebulifer• Range: Santa Cruz, CA to Magdalena Bay, Baja• Associated with sand/reef• Popular recreational fishery since 1970s• Mainland fishery (spawning Photo: author unknown aggregations)
    6. 6. Spotted Sand Bass, Paralabrax maculatofasciatus• Range: Monterey, CA to Mazatlan, Mexico/Gulf of Calif.• Associated with bays/harbors• Popular recreational fishery since 1980s• Mainland fishery (catch-and- release) Photo: Dave Rudie
    7. 7. Percent of Total Harvested Catch by Fishing Mode (California Recreational Fisheries Survey, 2004-2010) 100 80 Beach/Bank 60 Man-made% 40 69% 58% Private/rental 20 Party/charter 0 Barred sand bass Kelp bass Spotted sand bass
    8. 8. CPFV landings (1980-2011) Barred sand bass 85% decreaseFish kept Kelp bass 70% decrease
    9. 9. CPFV catch per unit effort (CPUE) (1980-2011) Barred sand bassCPUE (fish/angler) Kelp bass
    10. 10. Hyperstability and Population Size 10,000 k Populat g ion Size 1,000 k g 100 kg 10 kg Catch rates over timeModified from Larry G. Allen, 10-18-10
    11. 11. Hyperstability and Catch Ranges Catch range Catch when fish range are when fish abundant are scarce Catch rates North SouthModified from http://fish.washington.edu/
    12. 12. Fishery-Independent DatasetsDATA TYPE ORGANIZATION LIFE STAGELarval Abundance CalCOFI Larvae/recruitsRecruitment PISCOFish Entrapment Edison Sub-adultsGill Net Bycatch CSUN Hubbs Sea WorldSCUBA Surveys Reef Check Adults NPS PISCO Occidental College SF State Univ.
    13. 13. Mainland SCUBA Transects (1974-2009): Adults Barred sand bassMean density (fish/100 m2) 16 14 Kelp bass King Harbor Palos Verdes 12 10 8 6 4 2 0 1970 1975 1980 2000 2005 2010 1985 1990 1995
    14. 14. Island SCUBA Transects (1985-2010): Adults Kelp bass 12 10 Santa Cruz IslandMean density Anacapa Island 8 (fish/100 m2) 6 4 2 0 1990 1995 2000 2005 1985 2010
    15. 15. Entrapment Abundance (1975-2009): Subadults Barred sand bassMean abundance (fish/106 m3) Kelp bass
    16. 16. Rockbass Larval Abundance (1951-2010)Larvae per 10 m2
    17. 17. Pacific Decadal Oscillation
    18. 18. Rockbass Larval Abundance (1951-2010) Cold Regime Warm Regime CoolerLarvae per 10 m2
    19. 19. CPFV landings (1936-2011) Rockfish
    20. 20. Kelp bass densities and kelp canopy Juvenile Kelp Kelp bass 2 yr
    21. 21. Tracking Dominant Age Classes (Fishery Recruitment Strength) Barred sand bass 1997 year classDominant age (yrs) CPUE (fish/angler)
    22. 22. Tracking Dominant Age Classes (Fishery Recruitment Strength) Kelp bass 1997 year classDominant age (yrs) CPUE (fish/angler)
    23. 23. Recruitment and Larval Abundance Warm Regime Cool Warm CoolLarvae per 10 m2 Population recruitment failure? Decrease in larval survival and/or larval supply?
    24. 24. Size structure of harvested catch (1975-2011)Barred sand bass Est. Age (yrs) ~15+ 15+ 15+ 14 14 13 13 12 12 11 11 10 10Kelp bass 9 9 8 8 7 7 6 6 5 5 ~4 4 4
    25. 25. The Basses are Different• Steep catch declines • Smooth catch declines• Mainland fishery • Mainland/Island fishery• Very large, localized • Smaller, broadly spawning aggregations distributed spawning aggregations• Range less to the north • Range farther north • Kelp habitat important= HIGHER LEVEL OF CONCERN
    26. 26. Management Goals and Considerations1) Provide measures that will favor a population rebound for the basses. • Reduction in bag limit? • Change in size limit?
    27. 27. Management Goals and Considerations2) Protect barred sand bass spawning population. • Seasonal closure? • Seasonal reduction in bag limit?
    28. 28. Constituent Input Recreational Fishing Groups Bag limit reduction Slot limits No slot limits Minimum size limit increaseCatch-and-release only for spotted sand bass Environmental GroupsConcern for kelp bass and barred sand bass Explore management optionsPartial season closure for barred sand bass
    29. 29. Percent Reduction in Catch under Hypothetical Bag Limits In-season 3 fish bag limitData source: California Recreational Fisheries Survey, 2004-2010
    30. 30. Percent Reduction in Catch under Hypothetical Minimum Size LimitsData source: California Recreational Fisheries Survey, 2004-2010
    31. 31. Avg. Percent Reduction in Catch under Various 2-wk Closures Barred sand bass 50 40 30% 20 10 0 Wks 1-2 Wks 3-4 Wks 1-2 Wks 3-4 Wks 1-2 Wks 3-4 JUNE JULY AUGUST Data source: CPFV logbooks, 2004-2010
    32. 32. Summary• Environment and fishing have affected our bass populations• Precautionary management measures appear Artist: Kelly Day Spady prudent
    33. 33. Recommendations• Increase minimum size limit – Allows for at least 1 additional year of spawning• Decrease bag limit – Allows for modest savings• Partial spawning season closure – Allows for uninterrupted spawning activity
    34. 34. Recommendations• Continue to evaluate regulation effectiveness• Take adaptive management approach to maximize fishing opportunities Artist: Kelly Day Spady
    35. 35. Thank you

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