03-9058. Notice of Availability of Final Stock Assessment Reports

AGENCY:

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:

Notice of completion and availability of final marine mammal stock assessment reports; response to comments.

SUMMARY:

NMFS has incorporated public comments into revisions of marine mammal stock assessment reports (SARs). The 2002 final SARs are now complete and available to the public.

ADDRESSES:

Send requests for printed copies of reports to: Chief, Marine Mammal Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910-3226, Attn: Stock Assessments.

Copies of the Alaska Regional SARs may be requested from Robyn Angliss, Alaska Fisheries Science Center (F/AKC), NMFS, 7600 Sand Point Way, NE BIN 15700, Seattle, WA 98115-0070, e-mail [e-mail].

Copies of the Atlantic and Gulf of Mexico Regional SARs may be requested from Janeen Quintal, Northeast Fisheries Science Center, 166 Water St., Woods Hole, MA 02543, e-mail [e-mail] or Steven Swartz, Southeast Fisheries Science Center, 75 Virginia Beach Dr., Miami, FL 33149, e-mail [e-mail].

Copies of the Pacific Regional SARs may be requested from Cathy Campbell, Southwest Regional Office (F/SWO3), NMFS, 501 West Ocean Boulevard, Long Beach, CA 90802-4213, e-mail [e-mail].

FOR FURTHER INFORMATION CONTACT:

Tom Eagle, Office of Protected Resources, 301-713-2322, e-mail [e-mail]; Robyn Angliss 206-526-4032, regarding Alaska regional stock assessments; Janeen Quintal, 508-495-2252, regarding Northwest Atlantic regional stock assessments; Steven Swartz, 305-361-4487, regarding Mid-Atlantic and Gulf of Mexico regional stock assessments; or Cathy Campbell, 562-980-4020, regarding Pacific regional stock assessments.

SUPPLEMENTARY INFORMATION:

Electronic Access

All stock assessment reports and the guidelines for preparing them are available via the Internet at http://www.nmfs.noaa.gov/​prot_​res/​PR2/​ Stock_Assessment_Program/sars.html.

Background

Section 117 of the Marine Mammal Protection Act (MMPA) (16 U.S.C. 1361 et seq.) requires NMFS and the U.S. Fish and Wildlife Service (FWS) to prepare stock assessments for each stock of marine mammals that occurs in waters under the jurisdiction of the United States. These reports must, among other things, contain information regarding the distribution and abundance of the stock, population growth rates and trends, estimates of annual human-caused mortality and serious injury from all sources, descriptions of the fisheries with which the stock interacts, and the status of the stock. Initial reports were completed in 1995.

The MMPA requires NMFS and FWS to review the SARs at least annually for strategic stocks and stocks for which significant new information is available and at least once every 3 years for non-strategic stocks. NMFS and the FWS are required to revise a SAR if the status of the stock has changed or can be more accurately determined.

Draft 2002 SARs were made available for a 90-day public review and comment period on April 19, 2002 (67 FR 19417). Prior to their release for public review and comment, NMFS subjected the draft reports to internal technical review and to scientific review by regional Scientific Review Groups (SRGs) established under the MMPA. Following the close of the comment period, NMFS revised the reports as needed to prepare final 2002 SARs. Printed copies may be obtained by request (see ADDRESSES).

The FWS updated the most recent versions of the SARs for polar bears, sea otters, walrus, and manatees and they were appended to NMFS' final 2002 SARs. These reports were included so that interested constituents would have reports for all regional stocks in a single document.

Comments and Responses

NMFS received two letters, one from the National Wildlife Federation and the other from the Marine Mammal Commission (MMC) which contained comments on the draft 2002 SARs. The comments and responses below are separated according to the regional scope of the comments. Many of the comments on specific SARs addressed minor editorial points for clarification. Most of these comments were included into the final reports or will be included in future reports and are not included in the following segment of this document.

Comments on National Issues

Comment 1: Combining species groups is inconsistent with Sections 117 and 3(11) of the MMPA. Also, species with lower abundance, slower growth rates, and higher interaction (mortality and serious injury) rates may be more vulnerable to fisheries and other human activities, and the risk to those species may be increased when analyses are conducted on species groups.

Response: NMFS concurs that some populations or species may be more vulnerable to human-caused mortality than others; however, NMFS disagrees that stock assessment reports describing groups of populations or stocks are necessarily inconsistent with the MMPA. The MMPA states that stock assessment reports must be based upon the best scientific information available. In many cases, the best available information is limited to species groups. For example, in its initial SARs, NMFS reported on each species of beaked whale in a separate report, and most reports indicated that the species-specific abundance and mortality estimates used in management decisions were unknown. Thus, the species-specific reports were not informative. As a result, NMFS, in consultation with the SRGs, prepared subsequent reports for beaked whales and some other stocks as grouped reports. The information in these grouped reports must be interpreted with caution to avoid the conservation issues identified in this comment. When the methodologies to obtain data supporting stock-specific reports are available and sufficient data are collected, NMFS will use these methods to collect and analyze the appropriate information to prepare separate reports on each stock of beaked whale and other marine mammals where grouped data are used.

Comment 2: Requiring confirmation of human-caused effects to assess serious injuries and mortalities is contrary to the precautionary approach and incorporates several sources of negative bias; thus, it may not represent the best scientific information available. NMFS should report all injuries that could be serious and provide the rationale for discounting them in mortality estimates. An alternative approach, which was recommended in NMFS's 1997 workshop on differentiating serious and non-serious injuries would be to prorate cases where seriousness could not be determined using data from cases where such determination could be made. These approaches would provide a more realistic view of the uncertainty associated with the potential effects of fishing and other human activities.

Response: NMFS realizes that requiring evidence that human factors were, indeed, related to deaths of marine mammals could result in an underestimate of such mortality and may not be the most precautionary assessment of human-caused mortality. Most cases where we require such confirmation are those mortalities identified from stranded carcasses. These stranding records provide only minimum estimates of mortality, and the value of such data is related more to illustrating where quantitative data are needed rather than as substitutes for more reliable estimates. NMFS will continue using the summary approach in the SARs to realize the benefit of short documents that describe the status of each stock of marine mammal. Longer-more detailed discussion of this summary information will be contained in supporting reports and data, and this supporting information will continue to be cited in the reference section of each report.

Comment 3: The SARs are inconsistent in their use of observer data. For example, an observed mortality of one humpback whale as a result of a fishery interaction in the Pacific was not used as a basis for extrapolation because observer coverage was less than one percent; however, observer coverage of less than one percent is extrapolated for several Atlantic fisheries that appear to take large numbers of marine mammals. Also, the use of estimates based upon low levels of observer coverage and the use of a 5-year average fail to inspire confidence in the resulting estimates and are not sufficiently reliable to assess the efficacy of take reduction measures.

Response: In the case of the Central North Pacific stock of Humpback whales, the observed take was not used because it was more than 5 years old, not because only one mortality was observed. If the single observed take had been no more than 5 years old, the observed take would have been extrapolated to a mortality estimate. Thus, both reports are consistent with existing guidelines.

Uncertainty in mortality estimates due to low levels of observer coverage does, indeed, make it difficult to assess the efficacy of take reduction measures. However, low levels of observer coverage are primarily a result of budget limitations. NMFS considers monitoring in fisheries with an existing take reduction plan or in fisheries for which take reduction plans are being developed as its highest priorities. These priorities are consistent with priorities for observer coverage provided in the MMPA. NMFS gives priority to monitoring incidental takes and development and implementation of take reduction plans for commercial fisheries that have incidental mortality and serious injury of strategic stocks of marine mammals. Unfortunately, due to insufficient funding, NMFS will continue to have some fisheries for which incidental mortality estimates are highly uncertain due to low levels of observer coverage.

Comment 4: The Atlantic and Gulf of Mexico SAR does not adhere to the requirements of the MMPA regarding inclusion of descriptive data on fisheries that interact with marine mammals.

Response: The individual Atlantic and Gulf of Mexico SARs contain summary data for fisheries that interact with marine mammals. In addition a new table (Appendix I) has been added to the 2002 report, which provides the required information in summary form. Presenting the fishery descriptions in a single table avoids unnecessary duplication in the descriptions of fisheries where the same fishery interacts with several stocks of marine mammals.

Comment 5: Data standards need to be established to set the level of observer coverage for each fishery, particularly Atlantic trawl fisheries. The development and implementation of data standards should provide assurance that the effect of fisheries and other human activities are being assessed reliably.

Response: NMFS concurs that the level of observer coverage in Atlantic trawl fisheries has been insufficient to obtain reliable bycatch estimates. However, using data standards to set observer levels is not likely to alleviate this problem because observer coverage is limited by available funding.

Alaska Regional SARs

Comment 6: The SAR for the western stock of Steller sea lions includes fishery-specific mean annual mortality levels that are more than a decade old. The report should either explain why such data are considered reliable indicators of current take levels or remove the data from the table.

Response: NMFS agrees that some estimates of fishery-specific incidental mortality are quite old. Removing the data from the table would result in an apparent decrease in take level, which could lead the reader to conclude that mortalities have not occurred incidental to these fisheries. Thus, because these take levels constitute the best available information on the level of incidental mortality in these fisheries, the data will be retained in the table.

Comment 7: It is not clear why harbor seal stock structure designations in Alaska have not yet been changed. The genetics studies that are providing the basis for the revision were initiated 4 to 5 years ago, and the studies have since provided the best available scientific information upon which to base a revision of stocks. NMFS has been fully informed of the results and should have anticipated the possibility that they would indicate a more complex stock structure than was recognized in the past. The need for a stock-specific management program seems clear based on significant harbor seal declines in a number of locations in Alaska.

Response: NMFS is evaluating the stock structure of harbor seals in Alaska through a process that includes discussions with the Alaska Native Harbor Seal Commission under a co-management agreement. NMFS and the Harbor Seal Commission have discussed the available scientific information, and the next steps include compiling and incorporating Alaska Natives' knowledge into a recommended population structure.

Comment 8: The SAR for the eastern Chukchi Sea stock of beluga whales includes an estimate of 3,710 whales which is now based on data that are more than 8 years old. This estimate should be treated as outdated unless evidence can be provided that it is still a valid estimate.

Response: NMFS agrees that the estimate of 3,710 obtained from surveys conducted in 1989-91 would generally be considered outdated. However, the maximum count from surveys in 1998 (1,172 animals) is very similar to the maximum count during the summers of 1989-91 (- 1,200 animals). In addition, both counts are similar to those conducted in the summer of 1979. These counts indicate that no major changes in abundance have occurred; thus, the use of the older estimate is consistent with SAR guidelines. The SAR for this stock will next be reviewed in 2004; at that time, NMFS will revisit whether using this information for abundance is still appropriate.

Comment 9: The SAR for the Chukchi Sea stock of beluga whales does not provide sufficient information to distinguish between two alternative hypotheses: (1) There have been no takes of beluga whales as a result of gillnet and personal-use fisheries and (2) there have been takes but they have not been reported. The conclusion drawn is consistent with the first hypothesis, but the basis for distinguishing between these hypotheses is not clear and should be explained.

Response: The only data available to distinguish between these two hypotheses are contained in injury reports. No injuries (including mortalities) have been reported; therefore, the best available data support the hypothesis that no mortality incidental to the personal-use fisheries has occurred. Most beluga whales taken in personal-use fisheries are used for subsistence purposes and are reported as subsistence takes through the Alaska Beluga Whale Committee; thus, the estimate of total human-caused mortality is not significantly affected.

Comment 10: The SAR for the Cook Inlet stock of beluga whales indicates that there were no indications that the large stranding events from 1996-1999 resulted from human interactions. However, the information provided in the SAR does not indicate the nature and extent of efforts to determine the cause, so the reader cannot distinguish between (1) the events were unrelated to human activities and (2) the events were related to human activities but the relationship was not evaluated or detected. Essentially, it is not clear that the causes of the stranding events could be determined, and if this is the case, the SAR should state as much.

Response: The exact cause of the stranding cannot be determined. Stranding records and a knowledge of the dynamics of Cook Inlet (e.g., tidal changes) indicate that human factors were not responsible for the mass strandings.

Comment 11: The SAR for the Cook Inlet stock of beluga includes a statement in the section entitled “Habitat Concerns” that there is no indication that municipal, commercial, and industrial activities have had a quantifiable adverse impact on the beluga whale population. The absence of evidence in support of a particular hypothesis is not necessarily evidence that the hypothesis is false if a rigorous, powerful investigation has not been conducted.

Response: Specific investigations have not been carried out to determine whether municipal, commercial, and industrial activities have had a quantifiable adverse impact on the bowhead whale population. However, a review of the available information indicated that the observed population decline could be explained solely by subsistence harvest levels. Further, a review of available information on Cook Inlet beluga whales and their habitat did not provide any indication that activities other than the harvest were resulting in population-level effects.

Comment 12: The SAR for eastern North Pacific northern resident killer whale states that a population increases at the maximum growth rate only when the population is at extremely low levels; thus, the estimate of 2.92 percent is not a reliable estimate of Rmax. While this statement may be generally true, or at least is consistent with density-dependence theory, it is not necessarily always the case, particularly for K-selected species in fluctuating environments (e.g., where life history or vital rates are limited by biological rather than ecological factors). In these cases, growth rates could approximate Rmax at intermediate population levels.

Response: NMFS agrees that population growth rates could approximate Rmax at intermediate population levels. However, the generalized logistic model is the best available scientific information in this case. Under the logistic model, Rmax occurs only when population levels are low.

Comment 13: The AT1 group of transient killer whales is a discrete unit and should be a stock separate from the North Pacific transient killer whale stock.

Response: This comment was subsequently attached to a petition submitted to NMFS pursuant to section 115 of the MMPA requesting that the AT1 group of killer whales be recognized as a separate stock and designated as depleted. NMFS is currently evaluating the petition and will respond as required by the MMPA. If stock structure of transient killer whales in Alaska is modified as a result of this evaluation, NMFS will modify the SARs accordingly.

Comment 14: The range of observer coverage is not provided in Table 22 of the Gulf of Alaska harbor porpoise SAR. Although there is almost no observer coverage for gillnet fisheries that take harbor porpoise, the level of coverage should be provided.

Response: The SARs for harbor porpoise were not updated in 2002. These SARs will be updated in 2003 and information on the range of observer coverage will be provided at that time.

Comment 15: It is not clear how estimated mortality rates were calculated from observed mortality rates in the SARs for Dall's porpoise. For example, observed mortality in 1990 was 6, and at the 74 percent coverage, the estimated mortality should have been 8.

Response: The estimated mortality rates cannot be calculated directly by multiplying the observer coverage by the observed mortality for the Bering Sea/Aleutian Islands groundfish trawl fishery. The overall estimated mortality rates, which are provided in the SAR, were calculated by multiplying the observer coverage in each fishery management zone by the observed mortality rates in each zone and summing the estimated mortality levels per zone. The level of observer coverage reflected in the table is the average over all the zones. Thus, if the observer coverage in one area is very high, the estimated mortality level will be only slightly higher than the observed mortality level, as was the case in 1990.

Comment 16: The population size and minimum population abundance estimates for the central North Pacific humpback whale are both based on data from 1991-1993 and are, therefore, out of date.

Response: In 2002, NMFS convened a small workshop to begin the development of a new estimate for a portion of this stock, and preliminary information will be available to include in the draft SAR for 2003. Because the estimate based on the 1991-1993 information is the best available for this stock, it will be retained until a new estimate is available.

Comment 17: The SAR for the North Pacific right whale states that there are no known habitat issues for this stock and also indicates that the NMFS has been petitioned to designate critical habitat for this species. These two statements seem inconsistent. More importantly, a concern leading to the petition seems to have been ignored. The only recent observations of right whales have occurred in an area where much commercial fishing occurs. If whales are disturbed by fishing activities, their use of potentially important habitat may be precluded by the presence of fishing vessels and fishing operations that generate extensive noise.

Response: There is not necessarily an inconsistency simply because the SAR states no habitat concerns concurrently with NMFS receiving a petition to designate critical habitat. Although petitioners expressed a concern that commercial fishing vessels may disturb whales by generating excessive noise, preliminary results of studies conducted on North Atlantic right whales indicate the whales have not changed their distribution or behavior in response to vessel noise. It is premature to list vessel disturbance as a “concern” in the SAR until the impacts of vessel noise on behavior or distribution is better understood.

Atlantic Regional SARs

Comment 18: The section of the Western North Atlantic right whale SAR related to net productivity rates states that no population growth rate can be used because the population is in decline.

Response: NMFS changed the PBR of this stock of right whales to 0.0 in the 2000 revision of the SARs. At that time, it was estimated that the stock was not likely to recover to its Optimum Sustainable Population levels if there was any recurring human-caused mortality. Because the population remains small and critically endangered, NMFS continues to hold that position. Therefore, whether or not there is a value that could be reported for the maximum net productivity rate, NMFS maintains that the PBR for the stock is 0.0 and that this estimate is consistent with the definition of PBR.

Comment 19: The population estimate for the Western North Atlantic stock of blue whales is at least 15 years old, therefore, cannot be assumed to be a reliable, current estimate.

Response: NMFS agrees, and a blue whale PBR has not been calculated in the final report.

Comment 20: SARs should not be limited to records of mortality and serious injury that occur only in the U.S. Exclusive Economic Zone (EEZ). Similar to other species reports, all human caused mortality of Western North Atlantic blue whales should be included in the report.

Response: NMFS does not have mortality data on Western North Atlantic blue whales outside U.S. waters and is not aware of incidents of human-caused deaths or serious injury on this population.

Comment 21: The “Fishery Interaction” section of the SAR for common dolphins (Western North Atlantic stock) describes a pelagic longline fishery, but the level of take is not provided in the text or in Table 2.

Response: Although 16 common dolphins were killed incidental to the pelagic longline fishery between 1990-2000, no animals were killed or seriously injured during the 5-year period (1996-2000). Therefore, the data were not included in Table 2.

Pacific Regional SARs

Comment 22: For Hawaiian monk seals, the pattern of residuals in the graph showing mean number of non-pups by year suggests that the fitted model may be too linear, and other models should be investigated to provide a better fit. The title for the Y-axis overlaps the units of measurement and is difficult to read.

Response: NMFS is currently investigating other analyses to interpret the data more precisely. However, the slope of the current model provides an average rate of population decline during the entire period covered in the graph.

Comment 23: Data for population size of Hawaiian Monk Seals in 2001 are available, and it would be useful to include them in the discussion and the graph.

Response: Although the data for 2001 are currently available, the estimates resulting from these data were not completed and reviewed prior to completion of the 2002 draft SARs. The new estimates will be included in future drafts for public review and comment.

Comment 24: In the fourth paragraph in the Hawaiian monk seal section and in the section on Other Mortality, references to biotoxins (e.g., ciguatoxins) have been removed. Although mortality due to biotoxins has not been confirmed, it has long been a matter of concern stemming largely from (1) the 1978 mass mortality of seals at Laysan Island, which may have resulted from ciguatoxins, and (2) observations that monk seals consumed fish that were discarded during bottomfish operations because those fish are known to contain potentially high levels of biotoxins (i.e., were not considered fit for human consumption). The lack of confirmation that biotoxins do, in fact, cause mortality could indicate they do not, but it could also indicate that methods for detection or monitoring of such mortality are inadequate. In view of the fact that the potential threat posed to monk seals by biotoxins cannot be reliably characterized and concerns about such threats appear to be justified on the basis of the existing information on monk seals (as well as information on biotoxin effects on other marine mammal species), this potential source of mortality should be described in the report.

Response: The role of biotoxins, such as ciguatoxin, in mortality of monk seals remains speculative. Any number of other factors could also be hypothesized to cause mortality to monk seals, but are not listed because they are not confirmed. As relevant information becomes available, NMFS will include a summary of this information in the SARs, including the effects of biotoxins on monk seals.

Comment 25: In the Fisheries Information section, there was confusion over the total number of sets and hooks fished in Hawaiian waters.

Response: Two sets of values were presented: one for Hawaii-based vessels and another for vessels landing on the U.S. west coast (excluding Alaska and Hawaii). The reported value of 20.2 million hooks fished in 2000 refers to Hawaiian-based vessels, which corresponds to approximately 12,000 fishing trips, or 1,700 hooks per set. The cited value of 285 sets in year 2000 refers to boats landing on the continental U.S. west coast. Information on the number of Hawaiian-based sets will be clarified in the final stock assessment.

Comment 26: The commenter noted that the abundance of false killer whales in regions yet unsurveyed is unknown, nor has their presence been established in the Northwestern Hawaiian Islands. The commenter also suggested that it might be more accurate to state that current estimates are negatively biased, with the extent of the potential bias being unknown.

Response: The abundance of Hawaiian false killer whales outside of previously surveyed areas is unknown, but their presence has been documented through longline fishery interactions. Given even a low density of animals outside previously surveyed areas and the large expanse of the study area, new population estimates are likely to exceed the currently published estimate by an unknown amount. Thus the current aerial survey estimate represents an underestimate, owing to a lack of survey coverage throughout the stock's range. Current abundance estimates are also negatively-biased because correction factors for the proportion of animals missed by the survey aircraft due to diving (availability bias) and poor searching conditions (perception bias) are not available. A research cruise conducted in summer and autumn 2002 in the Hawaiian EEZ is expected to provide reliable estimates of abundance of false killer whales throughout the Hawaiian EEZ. Revised abundances estimates for Hawaiian cetaceans are expected to appear in the 2004 SARs, which will be reviewed by the Pacific SRG in late summer and fall of 2003 prior to public review and comment.

Comment 27: In Table 1 of the Fisheries Information section for harbor porpoise (Oregon/Washington coastal stock), estimates of mean annual take have not been included even though estimated mortality levels are included and, in most cases, are not zero. Although the observed mortality was recorded during experiments with pingers, it is not clear why the resulting take levels are not carried over into the final column.

Response: The mean annual take is included in Table 1 and is calculated as the average of the most recent 5 years of mortality estimates. The mean annual take of 9 (CV=0.62) harbor porpoise, calculated for the northern Washington marine set gillnet fishery in 1996-2000, includes mortality estimates for two of the years (1996 and 1997) in which acoustic alarm experiments were conducted in this fishery.

Dated: April 7, 2003.

Laurie K. Allen,

Acting Director, Office of Protected Resources, National Marine Fisheries Service.