Wildlife Health
Papahānaumokuākea

Why is it a concern?

For “key” species in marine sanctuaries (e.g., keystone species, foundation species, indicator species, and other focal species) measures of condition and health can be important in determining the likelihood that these species will persist and continue to provide vital ecosystem functions and services. Measures of health condition may include growth rates, fecundity, recruitment, age-specific survival, tissue contaminant levels, pathologies (disease incidence, tumors, deformities), injuries and the presence and abundance of critical symbionts or parasite loads.

The population and biomass status of apex predators, such as sharks and jacks, habitat-forming corals, and protected species such as turtles, monk seals and seabirds, varies considerably. Apex predators are in near pristine conditions and represent significant biomass. Habitat-forming coral and sea turtle populations appear to have stable populations and biomass. The endangered Hawaiian monk seal has experienced a 60 percent population decline since the 1950s and is currently found in critically low numbers. Pre-1950s declines were the result of human disturbance of habitats during island occupation and exploitation, expeditions, and hunting. Declines since the 1950s are most likely related to a combination of factors. Both adult and juvenile monk seals are preyed upon by sharks. Imbalances in male/female sex ratios in the population have increased levels of male aggression toward other males competing for access to fewer reproductively active females. Decadal shifts in patterns and availability of food has impacted adult reproductive capacity and juvenile survival. The overall shrinking population and altered sex ratios has resulted in inbreeding, reduced genetic variance, and relative poor fitness to tolerate environmental stress, such as lack of food. Other factors, such as marine debris entanglement and eating ciguatera tainted fish, have caused some deaths of adult and juvenile monk seals.

Increased sea surface temperatures have resulted in several coral bleaching events. The geographic distribution and extent of bleaching varies based on the specific site characteristics and latitude. Corals have not been affected, for the most part, by diseases and remain relatively pristine. The ecosystem’s pristine status provides the opportunity to evaluate the influence of anthropogenic activities on disease outbreaks.

Overview of Research

Science Needs and Questions

• What is causing the continued sex ratio imbalance and failure of females to survive to reproductive age?
• Does the main Hawaiian Island population have diminished genetic fitness similar to the Northwestern Islands population?
• What is the anticipated impact of sea-level change on coastal habitats and organism dependent on those habitats?
• What factors contribute to the occurrence and spread of coral diseases?

References

Antonelis, G.A., J.D. Baker, T.C. Johanos, R.C. Braun and A.L. Harting. 2004. Hawaiian monk seal (Monachus schauinslandi): status and conservation issues. Atoll Res. Bull. 543:75-101.

Balazs, G.H. and M. Chaloupka. 2003. Thirty-year recovery trend in the once depleted Hawaiian green sea turtle stock. Biol. Conserv. 117:491–498.

Bertilsson-Friedman, P.A. 2002. Shark inflicted injuries to the endangered Hawaiian monk seal, Monachus schauinslandi. M.S. Thesis, University of New Hampshire. 91 pp.

Clapp, R.B. and R.W. Woodward. 1972. The natural history of Kure Atoll, NWHI. Atoll Res. Bull. 164:303-304.

Craig, M.P. and T.J. Ragan. 1999. Body size, survival, and decline of juvenile Hawaiian monk seals, Monachus schauinslandi. Mar. Mammal Sci. 15(3):786-809.

Friedlander, A.M. and E.E. DeMartini. 2002. Contrasts in density, size, and biomass of reef fishes between the northwestern and the main Hawaiian Islands: the effects of fishing down apex predators. Mar. Ecol-Prog. Ser. 230:253-264.

Friedlander, A.M., G. Aeby, R. Brainard, A. Clark, E. DeMartini, S. Godwin, J. Kenyon, R. Kosaki, J. Maragos, P. Vroom. 2005. The state of coral reef ecosystems of the Northwestern Hawaiian Islands. pp. 270-311. In: J. Waddell (ed.), The state of coral reef ecosystems of the United States and Pacific freely associated states: 2005. NOAA Technical Memorandum, NOS NCCOS 11. NOAA/NCCOS Center for Coastal Monitoring and Assessment’s Biogeography Team. Silver Spring, MD. 522 pp. http://ccma.nos.noaa.gov/ecosystems/coralreef/coral_report_2005/NWHI_Ch10_C.pdf

Gilmartin, W.G. 1993. Research and management plan for the Hawaiian monk seal at French Frigate Shoals, 1993-96. Honolulu Lab., South-west Fisheries Science Center, Natl. Marine Fish. Serv., Admin. Rept. H-93-08. 22 pp.

Gilmartin, W.G., R.L. DeLong, A.W. Smith, L.A. Griner, M.D. Dailey. 1980. An investigation into unusual mortality in the Hawaiian monk seal, Monachus schauinslandi. In: Grigg, R.W. and R.T. Pfund (eds.). Proceedings of the Symposium on Status of Resource Investigation in the Northwestern Hawaiian Islands, April 24-25, 1980, p 32-41. Univ. HI, Sea Grant Rept. UNIHI-SEAGRANT-MR-80-04.

Henderson, J.R. 2001. A pre- and post-MARPOL Annex V summary of Hawaiian monk seal entanglements and marine debris accumulation in the Northwestern Hawaiian Islands, 1982-1998. Mar. Poll. Bull. 42:584-589.

Kenyon, K.W. 1972. Man versus the monk seal. J. Mammalogy 53(4):687-696. National Marine Fisheries Service (NMFS). 2007. Recovery Plan for the Hawaiian Monk Seal (Monachus schauinslandi). Second Revision. National Marine Fisheries Service, Silver Spring, MD. 165 pp.

Polovina, J.J., G.T. Mitchum, N.E. Graham, M.P. Craig, E.E. DeMartini, E.N. Flint. 1994. Physical and biological consequences of a climate event in the central North Pacific. Fish Oceanogr. 3:5-21.