Alan M. Friedlander

Predator-Induced Demographic Shifts in Coral Reef Fish Assemblages

In recent years, it has become apparent that human impacts have altered community structure in coastal and marine ecosystems worldwide. Of these, fishing is one of the most pervasive, and a growing body of work suggests that fishing can have strong effects on the ecology of target species, especially top predators. However, the effects of removing top predators on lower trophic groups of prey fishes are less clear, particularly in highly diverse and trophically complex coral reef ecosystems. We examined patterns of abundance, size structure, and age-based demography through surveys and collection-based studies of five fish species from a variety of trophic levels at Kiritimati and Palmyra, two nearby atolls in the Northern Line Islands. These islands have similar biogeography and oceanography, and yet Kiritimati has ∼10,000 people with extensive local fishing while Palmyra is a US National Wildlife Refuge with no permanent human population, no fishing, and an intact predator fauna. Surveys indicated that top predators were relatively larger and more abundant at unfished Palmyra, while prey functional groups were relatively smaller but showed no clear trends in abundance as would be expected from classic trophic cascades. Through detailed analyses of focal species, we found that size and longevity of a top predator were lower at fished Kiritimati than at unfished Palmyra. Demographic patterns also shifted dramatically for 4 of 5 fish species in lower trophic groups, opposite in direction to the top predator, including decreases in average size and longevity at Palmyra relative to Kiritimati. Overall, these results suggest that fishing may alter community structure in complex and non-intuitive ways, and that indirect demographic effects should be considered more broadly in ecosystem-based management.

US Coral Reefs in the Line and Phoenix Islands, Central Pacific Ocean: Status, Threats and Significance

This is the second of two chapters on the coral reefs of the five US Line and Phoenix Islands, consisting of Baker, Howland and Jarvis Islands, Kingman Reef, ; and Palmyra Atoll (Fig. 16.1). The previous chapter (Chapter 15, Maragos et al.) covers the history, geology, oceanography and biology, while this chapter covers the status, threats and significance of the five. All are low reef islets or atolls in the central Pacific Ocean administered by the US Fish and Wildlife Service as National Wildlife Refuges. These 5 Refuges are among 20 within the tropical Pacific and among 10 that protect coral reefs. Together they are geographically a part of the largest series of fully protected marine areas under unified management in the world.

Management implications of juvenile reef fish habitat preferences and coral susceptibility to stressors

In the Hawaiian Archipelago, shelter-dependent juvenile stages of many reef fishes and their coral habitats are increasingly put at risk by multiple anthropogenic stressors (e.g. overfishing and habitat loss, coral bleaching and sedimentation, respectively). We assessed coral bleaching (to identify relative susceptibility among growth forms) and the use v. availability of structurally complex and simple corals by juvenile reef fishes in Hawaii. We use these data in a model that identifies habitats and resource species for managing reef fisheries and conserving coral habitats. Many juvenile reef fishes preferentially inhabit rugose corals. The economic and ecological importance of these fishes varies from those with little value to others, such as highly prized parrotfishes that also serve as ecological engineers. Coral species also differ in their relative susceptibility to anthropogenic and natural stressors - more structurally complex corals tend to be more susceptible to stressors. Our model relates the economic and ecological valuations of fish resources with specific preferences of fish juveniles for corals of varying susceptibility, testing the prediction that risk should co-vary among species of corals and fishes. Managers should use such a model when prioritising habitats and resource species for conservation.

Traditional marine resources and their use in contemporary Hawai‘i

Marine resources were important to the ancient Hawai’ians for subsistence, culture and survival. But in recent times, intensive fishing pressure, particularly in more populated areas, has led to substantial declines in many highly prized and vulnerable species.2 Factors contributing to this include a growing human population, destruction of habitat, introduction of new and overly efficient fishing techniques (e.g. inexpensive monofilament gill nets, SCUBA,

Reef Fish - Chapter 4 Fishes. In Marine Biogeographic Assessment of the Main Hawaiian Islands

15 NOAA Southwest Fisheries Science Center, Marine Mammal and Turtle Division, CA, U.S.A. 16 University of Hawaiʻi at Mānoa, Joint Institute for Marine and Atmospheric Research, HI, U.S.A. 17 University of Hawaiʻi at Mānoa, HI, U.S.A. 18 NOAA Pacific Islands Fisheries Science Center, Protected Species Division, Cetacean Research Program, Honolulu, HI, U.S.A. 19 Nicholas School of the Environment, Duke University, NC, U.S.A. 20 NOAA Alaskan Fisheries Science Center, National Marine Mammal Laboratory, WA, U.S.A. 21 NOAA Pacific Islands Fisheries Science Center, Protected Species Division, Hawaiian Monk Seal Research Program, Honolulu, HI, U.S.A. ABSTRACT Marine mammals are ecologically, economically and culturally important to Hawaiʻi. Reliable information on species space-use patterns is required to inform marine spatial planning, particularly for offshore renewable energy installations. This chapter provides distribution maps for marine mammals observed in the U.S. waters of the Main Hawaiian Islands from 1993 to 2014 using data integrated from multiple sources and spatial predictive modeling. At least 26 species of marine mammal (one seal and 25 cetaceans) have been recorded across the project area, of which eight species are listed as Endangered. This chapter has two sections: 6.1 Cetaceans, and 6.2 Hawaiian monk seal. For cetaceans, maps are provided for 22 species, including 15 showing locations of sightings and seven showing predicted spatial distributions. Sighting data from aircraft, ships and small research vessels were integrated and modeled using non-linear algorithms to map summer and winter distributions. These models were based on the statistical relationships between cetacean abundance and environmental variables at the locations of sightings. Model performance ranged from 17 to 59 percent PDE (percentage deviance explained). Highest performing models were achieved for common bottlenose dolphin (Tursiops truncatus; 59% summer), spinner dolphin (Stenella longirostris; 56% winter) and humpback whale (Megaptera novaeangliae; 37% winter). All categories of predictors (survey platform, temporal, climatic, atmospheric, geographic, physical and biological oceanographic, and topographic), contributed to models, with depth, slope, surface current direction and the strengths of temperature and chlorophyll fronts being relatively important environmental predictors across models. For Hawaiian monk seal (Monachus schauinslandi), we provide maps of sighting locations, individual space-use patterns and the newly released critical habitat maps, followed by discussion of priorities for future data collection to support marine spatial planning. Chapter 6 Marine Mammals