Tempering Expectations of Recovery for Previously Exploited Populations in a Fully Protected Marine Reserve

Abstract

Centuries of resource extraction have impacted coral reef ecosystems worldwide. In response, area and fishery closures are often enacted to restore previously exploited populations and reestablish diminished ecosystem function. During the 19th and 20th centuries, monk seals, pearl oysters, and two lobster species were overharvested in the Northwestern Hawaiian Islands, now managed as the Papahānaumokuākea Marine National Monument, one of the largest conservation areas in the world. Despite years of protection, these taxa have failed to recover. Here, we review each case, discussing possible factors that limit population growth, including: Allee effects, interspecific interactions, and time lags. Additionally, large-scale climate changes may have altered the overall productivity of the system. We conclude that overfishing of coral reef fauna may have broad and lasting results; once lost, valuable resources and services do not quickly rebound to pre-exploitation levels. In such instances, management options may be limited to difficult choices: waiting hundreds of years for recovery, actively restoring populations, or accepting the new, often less desirable, alternate state.

Sailing through Time: A Historical Examination of the Explorations and Expeditions of the Papahānaumokuākea Marine National Monument

“…The significance of these islands as resting places for spirits and gods added to the importance of these geological landmarks. In fact, the first two islands in the NWHI chain, Nīhoa and Mokumanamana, were periodically inhabited between 1000 and 1700 A.D. (Emory 1928;Bryan 1978;Cleghorn 1988;Schultz et al, 2011). This is evidenced by a high abundance of artifacts including over 140 identified archaeological sites on these two islands alone, making them some of the densest scatters of prehistoric archaeological remains in Hawai'i (Emory 1928;Bryan 1978;Cleghorn 1988 (Yamase 1982).…”

“…Birds were not the only species to be hit, hunting of the Hawaiian monk seal, overexploitation of various fishery species and the near extinction of the pearl oyster at Pearl and Hermes Atoll occurred near the beginning of the 20 th century (Keenan et al;Shallenberger 2006;Schultz et al, 2011). The monk seals were hit early on, and their populations quickly went from abundant to meager due to the hunting of thousands of seals for their meat, skins and oils (Schultz et al, 2011).…”

“…The monk seals were hit early on, and their populations quickly went from abundant to meager due to the hunting of thousands of seals for their meat, skins and oils (Schultz et al, 2011). Excessive hunting led to a bottleneck in the Hawaiian monk seal population and by 1958, growing concerns mounted regarding group numbers.…”

“…Excessive hunting led to a bottleneck in the Hawaiian monk seal population and by 1958, growing concerns mounted regarding group numbers. As a result, the first monitoring and systematic beach survey programs began at this time (Schultz et al, 2011). Since then, field camps led by NOAA have been monitoring the critically threatened population of Hawaiian monk seals (Baker et al, 2012).…”

“…Since the 1930s, bottomfish and other fish stocks have been commercially harvested in the NWHI including nearshore fish species such as trevally, also known as ulua (Moffitt 1980;Kittinger et al, 2010). These fishing efforts became more notable following World War II and continued until the early 1990s (Moffitt 1980;Friedlander et al, 2005;Schultz et al, 2011). The black-lipped pearl oyster was no exception, with approximately 150,000 individuals harvested between 1928 and 1930 (Keenan et al, 2006;Shallenberger 2006).…”