Illegal shark fishing in the Galápagos Marine Reserve

Illegal shark fishing is thought to occur globally, including within so-called “shark sanctuaries”, marine reserves and even inside UNESCO World Heritage sites, such as the Galápagos Islands. Presumably, this is due to poor local enforcement coupled with the growing international demand (and high economic incentives) for shark and other wildlife products. Understanding illegal shark fishing practices, and specifically catch composition, is important as poaching is identified as a causal factor of global declines in shark populations. Unfortunately, reliable quantitative data on illegal shark fishing are scarce. Here, the catch onboard an illegal shark fishing vessel seized within the borders of the Galápagos Marine Reserve was documented. A total of 379 sharks from seven shark species were found onboard the vessel. A large fraction of the illegal catch was comprised of both female and juvenile sharks (64% and 89%, respectively). Despite numerous recent advances in shark conservation worldwide, this study demonstrates illegal shark fishing is an ongoing concern and that stricter enforcement and legislation is urgently needed, particularly in areas of high biodiversity.     

A governance analysis of the Galápagos Marine Reserve

The Galápagos Marine Reserve (GMR) has faced major governance challenges since its designation in 1998, largely due to the driving forces of immigration from the mainland; a heterogeneous population that has a mainland rather than an island identity; increasing demand for marine resources from global seafood markets; and the rapid growth of tourism. Until recently, the pressures related to these driving forces had challenged measures to promote the effectiveness of the GMR. Decisions taken through the participatory management structure were often undermined by a combination of civil unrest, illegal activities and lack of enforcement. A recent period of relative political stability, coupled with several new measures to address these driving forces, has improved the potential effectiveness of the governance framework. These measures include controls on immigration, the use of remote surveillance technologies to enforce fishing restrictions and a system for the improved management of tourism vessels. Whilst participative and economic incentives will continue to be important, increasing political will to promote long-term sustainability and related improvements in the use of legal incentives, including enforcement technologies and effective prosecutions for those who breach restrictions, are likely to be key elements of the governance framework. It is argued that these measures, coupled with the emergence of a more marine-aware generation of Galápagos citizens, should pave the way for major improvements in the effectiveness of the GMR, hopefully sufficiently strengthening the governance framework to withstand the major driving forces that could otherwise perturb it.     

The rocky path to sustainable fisheries management and conservation in the Galápagos Marine Reserve

Human activities in the Galápagos Marine Reserve are managed by a two-tier system involving a multi-stakeholder local participatory forum and a national inter-ministerial decision-making body. Despite efforts to achieve sustainable fisheries, the two main resources, spiny lobster and sea cucumber, have shown alarming signs of deterioration. The reasons for the management failure may lie in the design of the system, as Galápagos appears not to fulfill many of the critical enabling factors which facilitate successful common property management.     

Experimental study of wave–wave nonlinear interactions using the wavelet-based bicoherence

The wavelet-based bicoherence, which is a new and powerful tool in the analysis of nonlinear phase coupling, is used to study the nonlinear wave–wave interactions of breaking and non-breaking gravity waves propagating over a sill. Two cases of mechanically generated random waves based on Jonswap spectra are used for this purpose. Values of relative depth, k_ph (k_p is the wave number of the spectral peak and h is the water depth) for this study range between 0.38 and 1.22. The variations of wavelet-based total bicoherence for the test cases indicate that the degree of quadratic phase coupling increases in the shoaling region consistent with a wave profile that is pitched shoreward, relative to a vertical axis as seen in the experiments, but decreases in the de-shoaling region. For the non-breaking case, the degree of quadratic phase coupling continues to increase until waves reach the top of the sill. Breaking waves, however, achieve their highest level of quadratic phase coupling immediately before incipient breaking and the degree of phase coupling decreases sharply following breaking. In addition the wavelet-based bicoherence spectra provide evidence of the harmonics' growth which is reflected in the energy spectra. The bicoherence spectra also show that quadratic phase coupling between modes within the peak frequency as well as between modes of the peak frequency and its higher harmonics are dominant in the shoaling region, even though there are relatively high levels of quadratic phase coupling occurring between other frequencies. Furthermore, using the temporal resolution property of the wavelet-based bicoherence, we find that the quadratic wave interactions occur more readily during segments of time with large change of wave amplitude, rather than those segments having large wave amplitudes, but small gradients in amplitude.     

Modeling nonlinear wave–wave interactions with the elliptic mild slope equation

An approach is developed to simulate wave–wave interactions using nonlinear elliptic mild-slope equation in domains where wave reflection, refraction, diffraction and breaking effects must also be considered. This involves the construction of an efficient solution procedure including effective boundary treatment, modification of the nonlinear equation to resolve convergence issues, and validation of the overall approach. For solving the second-order boundary-value problem, the Alternating Direction Implicit (ADI) scheme is employed, and the use of approximate boundary conditions is supplemented, for improved accuracy, with internal wave generation method and dissipative sponge layers. The performance of the nonlinear model is investigated for a range of practical wave conditions involving reflection, diffraction and shoaling in the presence of nonlinear wave–wave interactions. In addition, the transformation of a wave spectrum due to nonlinear shoaling and breaking, and nonlinear resonance inside a rectangular harbor are simulated. Numerical calculations are compared with the results from other relevant nonlinear models and experimental data available in literature. Results show that the approach developed here performs reasonably well, and has thus improved the applicability of this class of wave transformation models.     

Island mass effect in the Juan Fernández Archipelago (33°S), Southeastern Pacific

Spatial and temporal variability of the island mass effect (IME; defined as local increases of phytoplankton associated with the presence of islands) at the Juan Fernández Archipelago (JFA) is analyzed using chlorophyll-a (Chl-a) satellite data, altimetry, sea surface temperature, wind, geostrophic currents and net heat flux over a ten year period (2002–2012). The the JFA islands (Robinson Crusoe-Santa Clara (RC-SC) and Alejandro Selkirk (AS)) present wakes with significant Chl-a increases, mainly during spring time. These wakes can reach Chl-a values of one order of magnitude higher (~1 mg m⁻³) than the surrounding oligotrophic waters (<0.1 mg m⁻³). The wakes are similar to von Kármán vortex streets which have been used to explain the impact of IME on Chl-a increases in numerical models. The wakes are formed from a high productivity area in the lee of the island, extending to the oceanic region as high Chl-a patches associated with submesoscale eddies that are detached from the islands and connected by less-productive zones. This pattern coincides with previous models that predict the effects of island-generated flow perturbations on biological production variability. The IME is a recurrent feature of islands that has even been observed in decadal average fields. In such average fields, the Chl-a values in RC-SC and AS islands can exceed values found in a Control Zone (a zone without islands) by ~50% and 30%, respectively. Seasonal and interannual variability reveals that, as a consequence of the IME, the winter Chl-a maximum associated with the development of winter convection and mesoscale eddies that propagate from the continental zone, promote that the Chl-a maximum extends towards spring. The IME has an impact on the island on both a local as well as a more regional scale that affects an area of ~40,000 km² (1°Latitude×4°Longitude) centered on the islands. The transport of high productivity patches associated with submesoscale eddies may be responsible for IME propagation at a regional scale. Around the islands, the presence of a weak oceanic incident flow and strong and recurrent wind-wakes, suggest that the generation of Chl-a wakes result from a combined effect between both forcings.     

The effect of wave–current interactions on the storm surge and inundation in Charleston Harbor during Hurricane Hugo 1989

The effects of wave–current interactions on the storm surge and inundation induced by Hurricane Hugo in and around the Charleston Harbor and its adjacent coastal regions are examined by using a three-dimensional (3-D) wave–current coupled modeling system. The 3-D storm surge and inundation modeling component of the coupled system is based on the Princeton ocean model (POM), whereas the wave modeling component is based on the third-generation wave model, simulating waves nearshore (SWAN). The results indicate that the effects of wave-induced surface, bottom, and radiation stresses can separately or in combination produce significant changes in storm surge and inundation. The effects of waves vary spatially. In some areas, the contribution of waves to peak storm surge during Hurricane Hugo reached as high as 0.76 m which led to substantial changes in the inundation and drying areas simulated by the storm surge model.