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Marine Mammal Protection Act; Stock Assessment Report

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Information about this document as published in the Federal Register.

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AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Notice of availability of final 2009 revised marine mammal stock assessment reports for two stocks of West Indian manatee; response to comments.

SUMMARY:

In accordance with the Marine Mammal Protection Act of 1972, as amended (MMPA), and its implementing regulations, we, the U.S. Fish and Wildlife Service (Service), announce that we have revised our stock assessment report (SAR) for each of the two West Indian manatee stocks in the southeastern United States: The Florida manatee (Trichechus manatus latirostris) stock and the Puerto Rico stock of Antillean manatee (Trichechus manatus manatus), including incorporation of public comments. We now make these two final 2009 revised SARs available to the public.

ADDRESSES:

To obtain the SARs for either or both of the West Indian manatee subspecies, see Document Availability under SUPPLEMENTARY INFORMATION.

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FOR FURTHER INFORMATION CONTACT:

West Indian Manatee in Florida: Jim Valade, (904) 731-3116 (telephone) or Jim_Valade@fws.gov (e-mail). West Indian Manatee in Puerto Rico: Marelisa Rivera, (787) 851-7297 (telephone) or Marelisa_Rivera@fws.gov (e-mail).

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SUPPLEMENTARY INFORMATION:

Background

Under the MMPA (16 U.S.C. 1361 et seq.) and its implementing regulations in the Code of Federal Regulations (CFR) at 50 CFR part 18, we regulate the taking, transportation, purchasing, selling, offering for sale, exporting, and importing of marine mammals. One of the MMPA's goals is to ensure that stocks of marine mammals occurring in waters under U.S. jurisdiction do not experience a level of human-caused mortality and serious injury that is likely to cause the stock to be reduced below its optimum sustainable population level (OSP). OSP is defined as “the number of animals which will result in the maximum productivity of the population or the species, keeping in mind the carrying capacity of the habitat and the health of the ecosystem of which they form a constituent element.”

To help accomplish the goal of maintaining marine mammal stocks at their OSPs, section 117 of the MMPA requires us and the National Marine Fisheries Service (NMFS) to prepare a SAR for each marine mammal stock that occurs in waters under U.S. jurisdiction. A SAR must be based on the best scientific information available; therefore, we prepare it in consultation with established regional scientific review groups. Each SAR must include: (1) A description of the stock and its geographic range; (2) a minimum population estimate, maximum net productivity rate, and current population trend; (3) an estimate of human-caused mortality and serious injury; (4) a description of commercial fishery interactions; (5) a categorization of the status of the stock; and (6) an estimate of the potential biological removal (PBR) level. The PBR is defined as “the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its OSP.” The PBR is the product of the minimum population estimate of the stock (Nmin); one-half the maximum theoretical or estimated net productivity rate of the stock at a small population size (Rmax); and a recovery factor (Fr) of between 0.1 and 1.0, which is intended to compensate for uncertainty and unknown estimation errors.

Section 117 of the MMPA also requires us and NMFS to review the SARs (a) at least annually for stocks that are specified as strategic stocks; (b) at least annually for stocks for which significant new information is available; and (c) at least once every 3 years for all other stocks.

A strategic stock is defined in the MMPA as a marine mammal stock (a) for which the level of direct human-caused mortality exceeds the PBR; (b) which, based on the best available scientific information, is declining and is likely to be listed as a threatened species under the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.; ESA), within the foreseeable future; or (c) which is listed as a threatened or endangered species under Start Printed Page 69137the ESA, or is designated as depleted under the MMPA.

Before releasing our draft SARs for public review and comment, we reviewed the drafts with the Atlantic Regional Scientific Review Group, which was established under the MMPA, and submitted them for an internal technical review. In a June 12, 2009 (74 FR 28062), Federal Register notice, we made available our draft SARs for the MMPA-required 90-day public review and comment period. Following the close of the comment period, we revised the SARs based on public comments we received (see below) and prepared the final 2009 revised SARs. Between publication of the draft and final revised SARs, we have not revised the status of either stock (i.e., strategic); however, we updated the Nmin for the Florida manatee stock from 3,807 to 3,802, based on a revised count provided by the Florida Fish and Wildlife Conservation Commission. We addressed other concerns identified in the public comments in the following section of this notice or by adding text to the SARs for clarity.

The following table summarizes the final 2009 revised SARs for the Florida and Puerto Rico stocks of the West Indian manatee, listing each stock's Nmin, Rmax, Fr, PBR, annual estimated human-caused mortality and serious injury, and status.

Table 1—Summary: Final Revised Stock Assessment Reports for the Florida and Puerto Rico Stocks of West Indian Manatee

West Indian manatee stocksNminRmaxFrPBRAnnual estimated average human-caused mortalityStock status
Florida3,8020.060.11287Strategic.
Puerto Rico720.040.102Strategic.

Document Availability

Final Revised SAR for West Indian Manatee in Florida

You may obtain copies by any one of the following methods:

  • Internet: http://www.fws.gov/​northflorida.
  • Write to or visit (during normal business hours) the Field Supervisor, U.S. Fish and Wildlife Service, Jacksonville Field Office, 7915 Baymeadows Way, Suite 200, Jacksonville, FL 32256-7517; telephone (904) 731-3336.

Final Revised SAR for West Indian Manatee in Puerto Rico

You may obtain copies by any one of the following methods:

Write to or visit (during normal business hours) the Field Supervisor, U.S. Fish and Wildlife Service, Caribbean Ecological Services Office, P.O. Box 491, Boquerón, PR 00667; telephone: (787) 851-7297.

Responding to Public Comments

West Indian Manatee in Florida

We received comments on the draft SAR (74 FR 28062) from the Atlantic Scientific Review Group, the Marine Mammal Commission, the Center for Biological Diversity, The Humane Society of the United States, the Save the Manatee Club, Defenders of Wildlife, and a private citizen. We present issues raised in those comments, along with our responses, below.

Comment 1: Commenters stated that the identification of four stocks would facilitate management efforts, because SARs, developed for each management unit, could more accurately identify unit-specific threats and, therefore, better promote recovery within the management units.

Response: Current and previous Florida manatee management activities have relied on the use of a state-of-the-art core biological model (CBM) to assess manatee population status and threats to the population as a whole and to assess status and threats in each of the four management units. Service and State manatee management efforts rely on the CBM for information on threats and consequently target identified threat levels through management activities described in respective recovery and management plans. For listed species, the Service uses recovery plans to identify and address threats as indicated by the ESA. Recovery Plans have been used effectively by the Service and other resource agencies for over 30 years. Unit-specific SARs for each of the four management units would be redundant and provide no additional benefits to efforts to manage manatees within these areas. As such, the Service will continue to assess and manage threats to the population as a whole and within each of the four management units. The SAR has been revised to more completely explain this strategy.

Comment 2: Commenters took issue with the Service's conclusion that total commercial fishery-related mortality and serious injury for the Florida stock of manatees should be considered insignificant and approaching a zero mortality and serious injury rate.

Response: For the period of record (2003-2007), manatee carcass salvage and rescue programs recorded no commercial fishery-related mortalities or any serious injuries related to commercial fisheries activities. While the total number of manatee deaths attributed to other anthropogenic sources exceeds the calculated PBR, the absence of deaths and serious injuries specifically from commercial fishing supports the Service's contention that commercial fisheries-related takings, in and of themselves, should be considered insignificant and approaching a zero mortality and serious injury rate.

Comment 3: Commenters stated that the Service's analysis of seriously injured manatees was problematic.

Response: Absent a Service definition of “serious injury,” an agency interpretation and analysis of manatee injury records is difficult at best and a thorough, meaningful analysis cannot be concluded at this time. The SAR has been revised to reflect this concern.

Comment 4: A commenter recommended that the Service include a table showing the results of abundance surveys over time.

Response: The Service elected not to include such a table because many readers may misinterpret differences in counts as indicative of changing population trends. The most recent minimum population estimate is the most significant, relevant data point and is included in the final SAR for the Florida manatee.Start Printed Page 69138

Comment 5: A commenter questioned the Service's determination that six cited fishing line and associated gear-related deaths did not involve actively fishing commercial fisheries-related gear.

Response: Each of the cited deaths involved the ingestion of lengths of monofilament line accompanied by a single hook, a lure, and/or a fishing weight. Given the manatees' herbivorous nature, it is unlikely that a manatee would be attracted to actively fished gear of this nature. Furthermore, nearshore, commercial fisheries that rely on gear of this nature are virtually unknown (commercial trotline fishers do fish in these waters; however, their gear typically includes lengths of monofilament line or other line types containing multiple hooks). Given the absence of inshore commercial line fisheries that utilize the gear found in these animals, these deaths should not be correlated with commercial fishing activities.

Comment 6: Two commenters questioned the use of an Rmax based on the maximum net productivity rate calculated for the Upper St. Johns River management unit.

Response: Guidance for developing SARs supports using measured growth rates greater than recommended default values, especially when using data that includes the entirety of a closed population to minimize unknown biases. Growth rates for the manatees in the Upper St. Johns River management unit have been accurately assessed and the population in this unit most closely approximates a closed population. As such, the Service believes that it has identified a proper Rmax.

Comment 7: Commenters questioned using serious injury and mortality data from the 2003 through 2007 period when more recent data are apparently available.

Response: Pertinent datasets used to prepare the SAR included data from the Florida Manatee Rescue, Rehabilitation, and Release Database and the Florida Manatee Mortality Database. At the time of writing, data from the manatee rescue program database were complete through December 31, 2007 and data for calendar year 2008 were not then available. Preliminary mortality database information was available through December 31, 2008, although data for calendar year 2008 had not been verified for accuracy at the time of writing. Consistent with mandates to use the best available information, the Service elected to use data from the 2003 through 2007 period inasmuch as data from this period had been thoroughly reviewed for completeness and accuracy at the time of writing.

Comment 8: Commenters recommended that the Service continue to take the steps needed to better define OSP and to gather more information on manatees in the Southwest management unit.

Response: The Service is supporting research activities that will provide greater insights into OSP for the Florida manatee and provide more current assessments of population trends and threat levels in both the stock and management unit populations.

West Indian Manatee in Puerto Rico

We received comments on the draft SARs (74 FR 28062) from the Atlantic Scientific Review Group, the Marine Mammal Commission, the Center for Biological Diversity, and The Humane Society. We present issues raised in those comments, along with our responses, below.

Comment 1: The Service should provide a better explanation for recognizing the Puerto Rico manatee as a single stock instead of recognizing the Puerto Rico manatee as consisting of different stocks based on the geographical distribution of haplotypes in Puerto Rico.

Response: We have revised the SAR to discuss recent research regarding the geographic distribution of haplotypes in Puerto Rico. Slone et al. 2006 indicates that haplotype (mitochondrial DNA) distribution is further geographically divided in Puerto Rico. For example, only the A haplotype (a haplotype also unique to Florida) was found on the north side of the island and only the B haplotype was observed in the south. A mixture of A and B haplotypes was observed on both the east and west coasts of the island, suggesting that mixing occurs between the northern and southern groups. However, the mitochondrial DNA is maternally inherited and is not reflective of gene flow from the more adventurous males. Radio-tagging techniques in Puerto Rico have documented general behavior of manatee populations, in which males seem to move more extensively than females (Slone et al. 2006). Males may travel hundreds of kilometers while mother/calf distribution patterns could be more restricted. The authors state that if male movements are made during the breeding season, then relatively healthy mixing between geographical areas established by females might be expected. Further research by Kellogg (2008) indicates that nuclear DNA subpopulation separation was not as severe, suggesting that the manatees in Puerto Rico do travel and breed throughout the population to some degree. Based on the above information, we believe that the Puerto Rico manatee stock should not be divided into two separate stocks.

Comment 2: The commenter suggested that the current population trend of the Puerto Rico manatee appears to be relatively stable rather than increasing.

Response: The Service agrees with the comment and has revised the SAR accordingly.

Comment 3: The commenter recommended that the statement “the number of strandings currently reported to DNER may represent a true value of mortality” should be considered as a hypothesis rather than a conclusion.

Response: The Service agrees and has revised the SAR accordingly.

Comment 4: The commenter recommended that the Service obtain information necessary to determine the optimum sustainable population (OSP).

Response: OSP has not been determined for any population stock of West Indian manatee; however, both the Florida and Puerto Rico stocks are considered strategic based on their listing under the ESA. From 1992-2002 and 2009, Service synoptic aerial surveys have consistently counted calves and the entire population is considered stable. We are evaluating aerial census methodology with the goal of establishing more reliable population estimates.

Comment 5: The commenter recommended the Service fill in data gaps by gathering more information on entanglements, collisions, and bycatch.

Response: As stated in the SAR, manatee deaths in Puerto Rico have been reported for decades. Since 1990, the documentation of manatee mortalities in Puerto Rico has been conducted by the Caribbean Stranding Network (CSN). In 2006, the Department of Natural and Environmental Resources (DNER) Marine Mammal Stranding Program (MMSP) took over these duties. This program is implemented with the assistance from the CSN, the Puerto Rico Zoo, and commonwealth law enforcement officials. We believe that the manatee death reports provided by the DNER MMSP, with all the help mentioned above, are a consistent and reliable manner to gather data on entanglements, collisions, and bycatch.

Comment 6: Commenters disagree with the Service's conclusion that commercial fisheries-related incidental mortality and serious injury of manatees in Puerto Rico and the U.S. Virgin Islands should be considered minimal or approaching zero.Start Printed Page 69139

Response: The Service acknowledges that there may be limitations on the available fisheries data because some takings could occur and may not be observed or reported. However, protocols for necropsies and assigning probable cause of death categories are reviewed thoroughly. Table 1 of this SAR shows watercraft as the only human related deaths. The only possible evidence for commercial fisheries interaction would be within the 34 percent undetermined cause of death (COD) category. Undetermined COD means that assessment of a natural or human related cause was negative (no evidence that COD can be assigned to any of the available categories, either natural or human related). In addition, we believe that manatees injured by commercial fisheries interactions would most likely present signs of the activity and every necropsy includes a specific evaluation of human interactions. From 1990-2008, only one manatee had COD related to commercial fisheries interaction. In 2006, one freshly dead manatee was found with its right flipper entangled in monofilament and still this COD was deemed undetermined. In accordance with the previous statements and the presence of current bans and restrictions prohibiting the use of nets in coastal Puerto Rican waters, the Service believes that incidental mortality and serious injury related to commercial fisheries in Puerto Rico and the U.S. Virgin Islands should be considered minimal or approaching zero.

Comment 7: The SAR should provide at least some summary information to indicate the type(s) of habitat degradation adversely affecting manatees.

Response: We have revised the SAR to include examples of habitat degradation.

Comment 8: The commenter recommended that the Puerto Rico manatee stock be considered separately from the Florida manatees in terms of recommendation for down-listing.

Response: The Service acknowledges the comment made; however, the SAR is conducted according to the MMPA and does not address issues under Section 4 of the ESA.

Comment 9: The commenter opposed any efforts to down-list the status of manatees from endangered to threatened.

Response: The Service acknowledges the comment made; however, the SAR is conducted according to the MMPA and does not address issues under Section 4 of the ESA.

Comment 10: The commenter is concerned about the lack of reliable data on abundance and mortality.

Response: The Service acknowledges the commenter's concern and is currently evaluating aerial census methods to establish more reliable population estimates. We do not believe that mortality records lack reliability. As provided in our response to Comment 5 above, CSN had been documenting manatee mortalities in Puerto Rico since 1990. Although the DNER MMSP took over these duties in 2006, the program is implemented with assistance from the CSN, the Puerto Rico Zoo, and commonwealth law enforcement officials. We believe that the manatee death reports provided by the DNER MMSP, with all assistance of these partners, are a consistent and reliable manner to gather mortality data.

Comment 11: The commenter asked why so many released manatees have died in Puerto Rico.

Response: After reviewing the data received by the CSN, we recognized there was an error and have revised the SAR accordingly. From 1990 to 2005, a total of 23 manatees were rescued by the CSN. Of these, two were rehabilitated and released, two were released immediately after rescue, 17 died in rehabilitation, one died in transport, and one is currently in rehabilitation. Of the four manatees that were released, one died one year after its release.

Additional References Cited

West Indian Manatee in Puerto Rico

Kellogg, M.E. 2008. Sirenian Conservation Genetics and Florida Manatee (Trichechus manatus latirostris) cytogenetics. Doctoral dissertation, University of Florida, Gainesville, FL. 159 pp.

Sloan, D.H., J.P. Reid, R.K. Bonde, S.M. Butler, and B.M. Stith. 2006. Summary of the West Indian manatee (Trichechus manatus) tracking by USGS-FISC Sirenia Project in Puerto Rico. Report Prepared for the U.S. Fish and Wildlife Service. 9 pp.

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Authority: The authority for this action is the Marine Mammal Protection Act of 1972, as amended (16 U.S.C. 1361 et al.).

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Dated: December 14, 2009.

Sam Hamilton,

Director, Fish and Wildlife Service.

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[FR Doc. E9-30900 Filed 12-29-09; 8:45 am]

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