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

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

Average length comparisons.

<p>(A) Comparison of average lengths in the commercial dataset versus the underwater visual survey dataset for the main Hawaiian Islands (MHI). Closed circles represent average lengths by species in different subregions of the MHI. (B) Average lengths observed in the Northwestern Hawaiian Islands versus simulated unexploited (pristine) average lengths. The red line represents perfect agreement between the two sets of average lengths. 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

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

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

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

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

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

Pharmaceutical Formulation Facilities as Sources of Opioids and Other Pharmaceuticals to Wastewater Treatment Plant Effluents

Facilities involved in the manufacture of pharmaceutical products are an under-investigated source of pharmaceuticals to the environment. Between 2004 and 2009, 35 to 38 effluent samples were collected from each of three wastewater treatment plants (WWTPs) in New York and analyzed for seven pharmaceuticals including opioids and muscle relaxants. Two WWTPs (NY2 and NY3) receive substantial flows (>20% of plant flow) from pharmaceutical formulation facilities (PFF) and one (NY1) receives no PFF flow. Samples of effluents from 23 WWTPs across the United States were analyzed once for these pharmaceuticals as part of a national survey. Maximum pharmaceutical effluent concentrations for the national survey and NY1 effluent samples were generally <1 μg/L. Four pharmaceuticals (methadone, oxycodone, butalbital, and metaxalone) in samples of NY3 effluent had median concentrations ranging from 3.4 to >400 μg/L. Maximum concentrations of oxycodone (1700 μg/L) and metaxalone (3800 μg/L) in samples from NY3 effluent exceeded 1000 μg/L. Three pharmaceuticals (butalbital, carisoprodol, and oxycodone) in samples of NY2 effluent had median concentrations ranging from 2 to 11 μg/L. These findings suggest that current manufacturing practices at these PFFs can result in pharmaceuticals concentrations from 10 to 1000 times higher than those typically found in WWTP effluents

Lower magnitude responses are less readily measured consistently across sites for ELISA and ICS IFNγ assays.

<p>Inter-site mean assay responses were plotted against the corresponding inter-site CVs for ELISA (A), ELISPot (B) and ICS (C) assays. Data from CD4+ T-cell and CD8+ T-cell ICS assays were combined. Lines are logarithmic regressions with R² values to indicate appropriateness of fit.</p