Removing observational noise from fisheries-independent time series data using ARIMA models

Abundance indices derived from fishery-independent surveys typically exhibit much higher interannual variability than is consistent with the within-survey variance or the life history of a species. This extra variability is essentially observation noise (i.e. measurement error); it probably reflects environmentally driven factors that affect catchability over time. Unfortunately, high observation noise reduces the ability to detect important changes in the underlying population abundance. In our study, a noise-reduction technique for uncorrelated observation noise that is based on autoregressive integrated moving average (ARIMA) time series modeling is investigated. The approach is applied to 18 time series of finfish abundance, which were derived from trawl survey data from the U.S. northeast continental shelf. Although the a priori assumption of a random-walk-plus-uncorrelated-noise model generally yielded a smoothed result that is pleasing to the eye, we recommend that the most appropriate ARIMA model be identified for the observed time series if the smoothed time series will be used for further analysis of the population dynamics of a species

The impact of marine reserves on exploited species with complex life histories: a modeling study using the Caribbean spiny lobster in Exuma Sound, Bahamas

Most benthic invertebrates and reef-associated fish undergo a dispersive, planktonic larval stage prior to settlement and metamorphosis into the juvenile and adult stages. In some species, settlement may be decoupled from adult abundance at local spatial scales if hydrodynamic conditions or larval behavior do not promote local retention. Similarly, spatial variability in postsettlement mortality or secondary dispersal by juveniles and adults may decouple spatial patterns of adult abundance from those of settlement. as a consequence, spatial patterns of settlement and adult abundance may be functionally related in a complex fashion. Whether biotic/environmental factors control spatial patterns of abundance may have profound implications for conservation of exploited benthic marine species, particularly when patterns of exploitation are themselves spatially structured as they are under management by marine reserves. As part of this dissertation, a spatially-explicit population dynamics model for the Caribbean spiny lobster in Exuma Sound, Bahamas was developed. The model is stage- and age-structured, and features dispersal of larvae from hatching sites via advection by hydrodynamic currents and diffusion, active migration of postlarvae into shallow nursery habitats, density-dependent survival and dispersal of benthic life-history stages (juveniles and adults), size-specific fecundity, and spatially-explicit exploitation rates. The population dynamics model was used heuristically to investigate the joint effects of reserve design (i.e., size, location, number), exploitation, population regulation and larval dispersal via hydrodynamic currents on population abundance and fishery yield. Principal findings were that fishery yield and larval production were idiosyncratic functions of reserve size, substantially influenced by interactions between current patterns and reserve location. Also, management strategies which implemented a single large reserve outperformed those using a network of small reserves, a reduction in total effort, or no action whatsoever. Results support the efficacy of marine reserves as a tool for rebuilding overexploited marine populations and creating sustainable fisheries. However, haphazard reserve creation may lead to a false sense of security, and poorly-designed reserves can perform worse than taking no action at all. Thus, designing successful marine reserves requires knowledge of local and regional patterns of hydrodynamic transport and larval dispersal, as well as other species\u27 life-history characteristics

A Deepwater Dispersal Corridor for Adult Female Blue Crabs in Chesapeake Bay

In marine ecosystems, there is no empirical evidence for the utility of dispersal corridors in conservation, despite widespread migrations by mammals, fish, and invertebrates. We investigated the potential for a deepwater dispersal corridor (\u3e 13 m depths) in protecting adult females of the blue crab, Callinectes sapidus, en route from shallow-water nursery and mating areas to the spawning sanctuary in lower Chesapeake Bay.https://scholarworks.wm.edu/vimsbooks/1128/thumbnail.jp

Efficacy of blue crab spawning sanctuaries in Chesapeake Bay

Sanctuaries can potentially protect a significant fraction of the spawning stock, and thereby sustain heavily exploited populations. Despite the worldwide use of marine and estuarine spawning sanctuaries, the effectiveness of such sanctuaries remains untested. We therefore attempted to quantify the effectiveness of the spawning sanctuaries for adult female blue crabs (Callinectes sapidus) in Chesapeake Bay. We used baywide winter dredge survey data to estimate the potential spawning stock prior to the major exploitation period, and summer trawl survey data to estimate spawning stock abundance within the Lower Bay Spawning Sanctuary and adjacent Bayside Eastern Shore Sanctuary during the reproductive period. Hence, we were able to approximate the percentage of the potential spawning stock that was protected by both sanctuaries after exploitation. On average, approximately 16% of the potential spawning stock survived to reach the Lower Bay Spawning Sanctuary and Bayside Eastern Shore Sanctuary. Even under a best-case scenario (i.e., crab residence time of 2 weeks), the sanctuaries only protected an estimated 22% of the potential spawning stock, which is well below the percentage recommended by recent stock assessments for sustainable exploitation (28%). In the worst case, a mere 11% of the potential spawning stock survived to reach the spawning sanctuaries. Hence, we recommend a substantial expansion of the spawning sanctuaries, as well as the complementary protection of other life stages in critical habitats, such as nursery grounds and dispersal corridors. Furthermore, traditional fisheries management measures (e.g., effort control) should be used in concert with sanctuaries to thwart impediments to effective implementation of the sanctuaries, such as redirected fishing effort.https://scholarworks.wm.edu/vimsbooks/1084/thumbnail.jp

Lessons on Marine Protected Area Management in Northern Boreal Regions from the United States and Norway

In comparison to tropical reef systems, relatively few marine protected areas (MPA’s) exist in temperate or subarctic systems (e.g., North Pacific and North Atlantic) where species diversity is lower, abundance of individual species is often higher, and many fish species exhibit large amounts of movement during one or more of their life stages, especially as adults. A review of MPA’s in three northern areas—the Northwest Atlantic, Northeast Atlantic, and the Northeast Pacific—indicates that MPA’s can be useful management tools towards fisheries management and habitat conservation. However, achieving fishery goals, such as sustainable use of the fisheries resources, will depend on population abundance (relative to unfished conditions) and fish behavior and movement. For example, depleted populations of stationary species such as Atlantic sea scallops, Placopecten magellanicus, in the Northeast Atlantic and European lobster, Homarus grammarus, in the North Sea have responded positively to small MPA’s, whereas migratory offshore Atlantic cod, Gadus morhua, and Pacific cod, Gadus macrocephalus, apparently do not appear to benefit from closed areas because of movement into fished areas. Efficient habitat conservation requires detailed habitat mapping on relevant spatial scales. In northern boreal systems with large remote areas, this information is difficult and expensive to access. An alternative strategy of closing and protecting unexploited areas has worked well for the Aleutian Island coral closure area in Alaska. MPA’s can be effective fisheries management tools when the species to be protected have been depleted and show a small to moderate level of movement, and reproductive success is ensured. MPA’s can be effective at preserving habitat when the design is based on scientific information and takes into account the impact on the user groups.publishedVersio

Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.