Populated and Remote Reefs Spanning Multiple Archipelagos Across the Central and Western Pacific

Comparable information on the status of natural resources across large geographic and human impact scales provides invaluable context to ecosystem-based management and insights into processes driving differences among areas. Data on fish assemblages at 39 US flag coral reef-areas distributed across the Pacific are presented. Total reef fish biomass varied by more than an order of magnitude: lowest at densely-populated islands and highest on reefs distant from human populations. Remote reefs (<50 people within 100 km) averaged ∼4 times the biomass of "all fishes" and 15 times the biomass of piscivores compared to reefs near populated areas. Greatest within-archipelagic differences were found in Hawaiian and Mariana Archipelagos, where differences were consistent with, but likely not exclusively driven by, higher fishing pressure around populated areas. Results highlight the importance of the extremely remote reefs now contained within the system of Pacific Marine National Monuments as ecological reference areas

National Oceanic and Atmospheric Administration Report 60

From abstract: This report contains single-species assessments of 27 reef-associated fish stocks around the main Hawaiian Islands using data from various sources collected during the 2003-2016 period

A stepwise stochastic simulation approach to estimate life history parameters for data-poor fisheries

Coastal fisheries are typically characterized by species-rich catch compositions and limited management resources which typically leads to notably data-poor situations for stock assessment. Some parsimonious stock assessment approaches rely on cost-efficient size composition data, but these also require estimates of life history parameters associated with natural mortality, growth, and maturity. These parameters are unavailable for most exploited stocks. Here, we present a novel approach that uses a local estimate of maximum length and statistical relationships between key life history parameters to build multivariate probability distributions that can be used to parameterize stock assessment models in the absence of species-specific life history data. We tested this approach on three fish species for which empirical length-at-age and maturity data were available (from Hawaii and Guam) and calculated probability distributions of spawning potential ratios (SPR) at different exploitation rates. The life history parameter and SPR probability distributions generated from our data-limited analytical approach compared well with those obtained from bootstrap analyses of the empirical life history data. This work provides a useful new tool that can greatly assist fishery stock assessment scientists and managers in data-poor situations, typical of most of the worldâ s fisheries.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Length-Based Assessment of Coral Reef Fish Populations in the Main and Northwestern Hawaiian Islands

<div><p>The coral reef fish community of Hawaii is composed of hundreds of species, supports a multimillion dollar fishing and tourism industry, and is of great cultural importance to the local population. However, a major stock assessment of Hawaiian coral reef fish populations has not yet been conducted. Here we used the robust indicator variable “average length in the exploited phase of the population (</p><p></p><p></p><p><mi>L</mi><mo>¯</mo></p><p></p><p></p>)”, estimated from size composition data from commercial fisheries trip reports and fishery-independent diver surveys, to evaluate exploitation rates for 19 Hawaiian reef fishes. By and large, the average lengths obtained from diver surveys agreed well with those from commercial data. We used the estimated exploitation rates coupled with life history parameters synthesized from the literature to parameterize a numerical population model and generate stock sustainability metrics such as spawning potential ratios (SPR). We found good agreement between predicted average lengths in an unfished population (from our population model) and those observed from diver surveys in the largely unexploited Northwestern Hawaiian Islands. Of 19 exploited reef fish species assessed in the main Hawaiian Islands, 9 had SPRs close to or below the 30% overfishing threshold. In general, longer-lived species such as surgeonfishes, the redlip parrotfish (<i>Scarus rubroviolaceus</i>), and the gray snapper (<i>Aprion virescens</i>) had the lowest SPRs, while short-lived species such as goatfishes and jacks, as well as two invasive species (<i>Lutjanus kasmira</i> and <i>Cephalopholis argus</i>), had SPRs above the 30% threshold.<p></p></div

Spawning potential ratio (SPR) for 19 Hawaiian reef fishes in the main Hawaiian Islands.

<p>White bars, SPR < 25%; gray bars, SPR between 25% ≤ SPR ≤ 35%; black bars, SPR > 35%. Species codes are defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133960#pone.0133960.t002" target="_blank">Table 2</a>. Dashed line denotes minimum SPR threshold of 30%.</p

Time-series of average lengths in the exploited phase of the population.

<p>Average lengths displayed for 9 Hawaiian reef fish species in the MHI from 2003 to 2012. Species included in this analysis had at least 30 length observations per year. Data from commercial fishery reports. Species codes are defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133960#pone.0133960.t002" target="_blank">Table 2</a>.</p

Example of yield-per-recruit isopleths.

<p>Yield as a function of fishing mortality rates (F) and sizes at first capture (<i>L</i>_<i>c</i>) for the giant trevally <i>Caranx ignobilis</i>. <i>Y</i>_curr represents current yield-per-recruit (in kg) in the fishery and <i>Y</i>_eum is the highest possible yield for the current <i>F</i> (0.4). The gray area represents combinations of <i>F</i> and <i>L</i>_<i>c</i> that result in SPRs below 30%. <i>L</i>_<i>c</i> eum is the minimum size limit that will maximize yield while <i>L</i>_<i>c</i> SPR30 is the minimum size limit that will lead to an SPR of 30% given the current <i>F</i>.</p

Information summary of the two principal regions of the Hawaiian Islands, including the four subregions of the main Hawaiian Islands.

<p>^a Channel widths from east to west.</p><p>Information summary of the two principal regions of the Hawaiian Islands, including the four subregions of the main Hawaiian Islands.</p

Life history parameters, mortality rates, and sustainability benchmarks for 19 Hawaiian reef fishes.

<p><i>* UVC data used for average length</i>. <i>All other species</i>, <i>commercial data used</i>.</p><p>See text for description of life history parameters and symbols used. Only species with at least 30 length observations were analyzed. Potential yield increase is the increase in yield that would result if fishing is eumetric (L_c = L_c eumetric). Lc SPR30 is the minimum size at full selectivity for SPR to be equal to 30% under current fishing mortality rate (F). See the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133960#pone.0133960.s001" target="_blank">S1 Table</a> for life history parameter references.</p

Average lengths (L¯) and 95% CIs for the main Hawaiian Islands (MHI; open circles) and the Northwestern Hawaiian Islands (NWHI; closed circles).

<p>Two reference points are also displayed: first red bar, </p><p></p><p></p><p></p><p></p><p><mi>L</mi><mo>¯</mo></p><p><mi>S</mi><mi>P</mi><mi>R</mi><mn>30</mn></p><p></p><p></p><p></p><p></p> (average length when SPR = 30%); second red bar, <p></p><p></p><p></p><p></p><p><mi>L</mi><mo>¯</mo></p><p><mi>F</mi><mo>=</mo><mn>0</mn></p><p></p><p></p><p></p><p></p> (average length when F = 0). Species are ordered by maximum size. Only species with n>30 in the NWHI are presented. Species codes are defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0133960#pone.0133960.t002" target="_blank">Table 2</a>.<p></p