An Ecosystem-Based Approach to Evaluating Impacts and Management of Invasive Lionfish

<p>Species invasions in marine ecosystems pose a threat to native fish communities and can disrupt the food webs that support valuable commercial and recreational fisheries. In the Gulf of Mexico, densities of invasive Indo-Pacific Lionfish, <i>Pterois volitans</i> and <i>P. miles</i>, are among the highest in their invaded range. In a workshop setting held over a 2-week period, we adapted an existing trophic dynamic model of the West Florida Shelf, located in the eastern Gulf of Mexico, to simulate the lionfish (both species) invasion and community effects over a range of harvest scenarios for both lionfish and native predators. Our results suggest small increases in lionfish harvest can reduce peak biomass by up to 25% and also that reduced harvest of native reef fish predators can lead to lower lionfish densities. This model can help managers identify target harvest and benefits of a lionfish fishery and inform the assessment and management of valuable reef fish fisheries.</p

The CBA-N2a detectable CTX concentrations in lionfish from two of the sampling locations are shown as C-CTX-1 eq. values in ppb.

<p>The number of fish analyzed at each location was 11 for the British Virgin Islands (BVI) and 5 for the Florida Keys. C-CTX-1 was confirmed by LC-MS/MS (denoted by an *) in six of the samples from BVI and one from Florida Keys. The horizontal dashed line indicates the FDA guidance level of 0.1 ppb for C-CTX-1 eq.</p

Ciguatoxin concentrations in lionfish reported from two previous studies done in the Lesser Antilles and US Virgin Islands determined by CBA-N2a compared to the CTX estimates found in this study.

<p>ND = CTX activity not detected.</p

Time Series of RBA_(F) Reaction.

<p>RBA_(F) standard curves of percent (%) binding versus P-CTX-3C (g mL^-1) where the standards were allowed to incubate with the synaptosomes for 1.5 (open circle), 3.0 (open triangle) and 4.0 h (open square).</p

Map showing distribution of sampling sites where fish were collected.

<p>Sample sites located within each location are identified as “n”.</p

Range of reported C-CTX-1 concentrations for Caribbean and Gulf of Mexico fish other than lionfish.

<p>Range of reported C-CTX-1 concentrations for Caribbean and Gulf of Mexico fish other than lionfish.</p

LC-MS/MS chromatogram for confirmation of C-CTX-1.

<p>The chromatogram shows the three characteristic confirmatory ion transitions (<i>m/z</i> 1123.6 > 1105.6, 1123.6 > 1087.6, and 1123.6 > 1069.9) and the retention time (4.8 min) of a C-CTX-1 standard and in lionfish.</p

RBA_(F) Sample Binding Curves.

<p>Representative RBA_(F) curves of 1:3 serially diluted of fish samples spiked with 0 (open diamond), 0.050 (open circle), 0.075 (open triangle), and 0.100 ppb (open square) P-CTX-3C with percent (%) binding versus fish extract concentration (g mL^-1). The detection limit (small dashed line) was 0.075 ppb P-CTX-3C and the limit of quantitation (larger dashed line) was 0.100 ppb P-CTX-3C.</p

RBA_(F) and RBA_(R) Linear Standard Curves.

<p>Lower ciguatoxin concentrations found in fish surveyed in this study were accurately measured using a linear standard curve consisting of 0.10, 0.25, 0.50 and 1.0 ppb P-CTX-3C. Results were equivalent for the RBA_(F) (open circle; solid line) and RBA_(R) (closed triangle; dashed line) (t-test, P = 0.982).</p

LC-MS/MS Confirmation of Ciguatoxins.

<p>LC-MS/MS chromatogram showing the retention time (4.76 min) and the three characteristic ion transitions (1123.6 > 1105.6, 1123.6 > 1087.9, and 1123.6 > 1069.6) of a C-CTX-1 standard and in a lionfish sample.</p