Lionfish Pterois volitans and P. miles have spread rapidly throughout the Caribbean Sea since 1985, where they negatively impact native fish communities and therefore are considered by some as the most damaging invasive species in the Caribbean to date. To combat further population growth and spread of lionfish and to protect native fish communities, various Caribbean islands have started control efforts. On Bonaire, a removal program based on volunteers using spear guns was started immediately after the first lionfish was sighted in 2009, and a similar program was started on neighboring Curaçao 2 yr later. To determine the effectiveness of these removal efforts, differences in the density and biomass of lionfish were compared between areas in which lionfish were directly targeted during removal efforts (i.e. 'fished' areas) on Bonaire and areas where they were not (i.e. 'unfished areas') on both Bonaire and Curaçao. Lionfish biomass in fished locations on Bonaire was 2.76-fold lower than in unfished areas on the same island and 4.14-fold lower than on unfished Curaçao. While removal efforts are effective at reducing the local number of lionfish, recruitment from unfished locations, such as those too deep for recreational diving and at dive sites that are difficult to access, will continuously offset the effects of removal efforts. Nevertheless, our results show that the immediate start and subsequent continuation of local removal efforts using volunteers is successful at significantly reducing the local density and biomass of invasive lionfish on small Caribbean islands. KEY WORDS: Spearfishing · Eradication of lionfish · Pterois volitans · Invasive species · Curaçao · BonaireResale or republication not permitted without written consent of the publisher Endang Species Res 22: 175-182, 2013 time, and as a result, local and rapid response efforts are often not sufficiently considered as a (temporary) alternative to international action to minimize the effect of marine invasives, despite the fact that such rapid response strategies are sometimes successful (Anderson 2005, Frazer et al. 2012.All aforementioned aspects are relevant to management efforts aimed at minimizing the negative effects of the invasive Pacific lionfish Pterois volitans and P. miles on native marine communities in the Atlantic Ocean. P. volitans/miles were first sighted in the Atlantic region near the southeast coast of North America in 1985, where they had likely been released by aquarists (Semmens et al. 2004). From there, they first spread northward along the east coast of the USA and since 2004 also southward toward the Caribbean Sea, the Gulf of Mexico and the north coast of South America (Schofield 2009, 2010, Johnston & Purkis 2011, Frazer et al. 2012). In the Caribbean, lionfish have established themselves in a variety of marine habitats, including coral reefs, mangroves, sea grass beds, coastal estuaries and deep waters up to 300 m (Barbour et al. 2010, Biggs & Olden 2011, Jud et al. 2011. They are generalist predators of...

The retreating ice cover of the Central Arctic Ocean (CAO) fuels speculations on future fisheries. However, very little is known about the existence of harvestable fish stocks in this 3.3 million–square kilometer ecosystem around the North Pole. Crossing the Eurasian Basin, we documented an uninterrupted 3170-kilometer-long deep scattering layer (DSL) with zooplankton and small fish in the Atlantic water layer at 100- to 500-meter depth. Diel vertical migration of this central Arctic DSL was lacking most of the year when daily light variation was absent. Unexpectedly, the DSL also contained low abundances of Atlantic cod, along with lanternfish, armhook squid, and Arctic endemic ice cod. The Atlantic cod originated from Norwegian spawning grounds and had lived in Arctic water temperature for up to 6 years. The potential fish abundance was far below commercially sustainable levels and is expected to remain so because of the low productivity of the CAO.

No abstract

With the increasing anthropogenic impacts on fish habitats, it has become more important to understand which primary resources sustain fish populations. This resource utilization can differ between fish life stages, and individuals can migrate between habitats in search of resources. Such lifetime information is difficult to obtain due to the large spatial and temporal scales of fish behavior. The otolith organic matrix has the potential to indicate this resource utilization and migration with δ13C values of essential amino acids (EAAs), which are a direct indication of the primary producers. In a proof‐of‐concept study, we selected the Acoupa weakfish, Cynoscion acoupa, as a model fish species with distinct ontogenetic migration patterns. While it inhabits the Brazilian mangrove estuaries during juvenile stages, it moves to the coastal shelf as an adult. Thus, we expected that lifetime resource utilization and migration would be reflected in δ13CEAA patterns and baseline values in C. acoupa otoliths. By analyzing the C. acoupa otolith edges across a size range of 12–119 cm, we found that baseline δ13CEAA values increased with size, which indicated an estuarine to coastal shelf distribution. This trend is highly correlated with inorganic δ13C values. The δ13CEAA patterns showed that estuarine algae rather than mangrove‐derived resources supported the juvenile C. acoupa populations. Around the juvenile size of 40 cm, resource utilization overlapped with those of adults and mean baseline δ13CEAA values increased. This trend was confirmed by comparing otolith core and edges, although with some individuals potentially migrating over longer distances than others. Hence, δ13CEAA patterns and baseline values in otoliths have great potential to reconstruct ontogenetic shifts in resource use and habitats. The insight could aid in predictions on how environmental changes affect fish populations by identifying the controlling factors at the base of the food web.

A rapidly warming Arctic Ocean and associated sea‐ice decline is resulting in changing sea‐ice protist communities, affecting productivity of under‐ice, pelagic, and benthic fauna. Quantifying such effects is hampered by a lack of biomarkers suitable for tracing specific basal resources (primary producers and microorganisms) through food webs. We investigate the potential of δ13C values of essential amino acids (EAAs) (δ13CEAA values) to estimate the proportional use of diverse basal resources by organisms from the under‐ice (Apherusa glacialis), pelagic (Calanus hyperboreus) and benthic habitats (sponges, sea cucumber), and the cryo‐pelagic fish Boreogadus saida. Two approaches were used: baseline δ13CEAA values, that is, the basal resource specific δ13CEAA values, and δ13CEAA fingerprints, or mean‐centred baseline δ13CEAA values. Substantial use of sub‐ice algae Melosira arctica by all studied organisms suggests that its role within Arctic food webs is greater than previously recognized. In addition, δ13CEAA fingerprints from algae‐associated bacteria were clearly traced to the sponges, with an individually variable kelp use by sea cucumbers. Although mean‐centred δ13CEAA values in A. glacialis, C. hyperboreus, and B. saida tissues were aligned with microalgae resources, they were not fully represented by the filtered pelagic‐ and sea‐ice particulate organic matter constituting the spring diatom‐dominated algal community. Under‐ice and pelagic microalgae use could only be differentiated with baseline δ13CEAA values as similar microalgae clades occur in both habitats. We suggest that δ13CEAA fingerprints combined with microalgae baseline δ13CEAA values are an insightful tool to assess the effect of ongoing changes in Arctic basal resources on their use by organisms.