Effectiveness of fishing gears to assess fish assemblage size structure in small lake ecosystems

2014 ◽  
Vol 21 (3) ◽  
pp. 211-219 ◽  
Author(s):  
T. A. Clement ◽  
K. Pangle ◽  
D. G. Uzarski ◽  
B. A. Murry
Keyword(s):  
Fish Assemblage ◽  
Size Structure ◽  
Lake Ecosystems ◽  
Small Lake ◽  
Fishing Gears ◽  
Assemblage Size

Analysis of crab size structure and the fishing effort applied to a crab fishery in northwest Mexico

Crustaceana ◽  
2018 ◽  
Vol 91 (2) ◽  
pp. 225-237 ◽  
Author(s):  
César A. Heredia-Delgadillo ◽  
Guillermo Rodríguez-Domínguez ◽  
Raúl Pérez-González ◽  
Nicolás Castañeda-Lomas ◽  
Sergio G. Castillo-Vargasmachuca ◽  
...  
Keyword(s):  
Gulf Of California ◽  
Size Structure ◽  
Coastal Lagoons ◽  
Low Frequency ◽  
Fishing Effort ◽  
Double Ring ◽  
Northwest Mexico ◽  
Fishing Gears ◽  
Fishery Cooperatives ◽  
Ring Net

The fishing effort of a Sinaloa crab fishery in the Gulf of California in 2014 was analysed based on fishermen’s interviews, official catches and permits, and information from a sample of fishing logbooks from five fishery cooperatives operating in four coastal lagoons that contained the daily catch from individual fishing trips. Unauthorized gear, a double-ring net (DR), was used most frequently (>70% of the fishers) for crab fishing, although authorized single-ring nets and Chesapeake traps (CT) were also used with low frequency. The estimated fishing effort was 641 boats/day in the four coastal lagoons, which was 34% more than authorized, and 818 boats/day were employed in all of Sinaloa. A total of 57 479 fishing gears were estimated for the study area, which was 49.9% greater than the maximum authorized number, and 80 822 nominal fishing gears were estimated for the entire Sinaloa crab fishery, 14.15% more than the total gear limit (70 800). The size of the mesh used in the gear was smaller than the authorized limit of 76 mm, and >50% of the catches included crabs of unlawful size. It is argued that the effort must be regulated in terms of the number of vessels, per unit time, and not the number of gears. The information from this study demonstrates a failure to monitor compliance with current regulations and thus means that other strategies for the sustainable management of the fishery, such as co-management, should be tested.

scholarly journals Soil salinization processes in small-lake Ballestera wetland ecosystem (La Lantejuela, Seville, Spain)

2019 ◽  
Vol 19 (1) ◽  
pp. 22-25
Author(s):  
F. Diaz del Olmo ◽  
J. M. Recio Espejo ◽  
C. Borja Barrera ◽  
R. Cámara Artiga
Keyword(s):  
Electric Conductivity ◽  
Soil Salinization ◽  
Salt Accumulation ◽  
Lake Ecosystems ◽  
Small Lake ◽  
Natural Reserve ◽  
Confined Environment ◽  
Surface Crust ◽  
Black Color ◽  
Semiarid Conditions

Salinization processes in soils with thermo-mediterranean-semiarid conditions within a confined environment (basin closed) are studied in Natural Reserve Ballestera small-lake ecosystems (Seville, Spain). Methodologically it is carried out a geopedological catena integrated by five drilling-profiles with depths between 0.20 and 1.50 m. A total of 21 pedo-sedimentary samples have been characterized through pH, electric conductivity, carbonates contents, magnetic susceptibility and texture determinations. The results show the presence of two different phases in the geopedological evolution of the ecosystem: one of them is previous to the geomorphological constitution of the existing wetland, characterized by carbonates and salts lateral lixiviation processes (vertisolization-tirsification processes determinant of a special black color in the soil), and the second one, later and current, distinguishing processes of salt accumulation (saline brines) and surface crust formations (saltcrete) of halite and gypsum with high value of electric conductivity (salinization and hydromorphic processes).

Cell-, biovolume- and biosurface-specific energy fluxes through marine picoplankton as a function of the assemblage size structure

2007 ◽  
Vol 458 (1-2) ◽  
pp. 23-33 ◽  
Author(s):  
Vladimir S. Mukhanov ◽  
Olga G. Naidanova ◽  
Olga A. Lopukhina ◽  
Richard B. Kemp
Keyword(s):  
Specific Energy ◽  
Size Structure ◽  
Energy Fluxes ◽  
Cell Biovolume ◽  
Assemblage Size

Structure and composition of metal particles in Pt-Sn/Al2O3 bimetallic catalysts

1990 ◽  
Vol 48 (4) ◽  
pp. 278-279
Author(s):  
A. Sachdev ◽  
J. Schwank
Keyword(s):  
Bimetallic Catalysts ◽  
Bimetallic Catalyst ◽  
Size Structure ◽  
High Surface ◽  
High Surface Area ◽  
Metal Particles ◽  
Alloy Formation ◽  
Particle Size Range ◽  
Oxide Supports ◽  
Petroleum Fractions

Platinum - tin bimetallic catalysts have been primarily utilized in the chemical industry in the catalytic reforming of petroleum fractions. In this process the naphtha feedstock is converted to hydrocarbons with higher octane numbers and high anti-knock qualities. Most of these catalysts contain small metal particles or crystallites supported on high surface area insulating oxide supports. The determination of the structure and composition of these particles is crucial to the understanding of the catalytic behavior. In a bimetallic catalyst it is important to know how the two metals are distributed within the particle size range and in what way the addition of a second metal affects the size, structure and composition of the metal particles. An added complication in the Pt-Sn system is the possibility of alloy formation between the two elements for all atomic ratios.

Effects of marine reserves on predator-prey interactions in central California kelp forests

2020 ◽  
Vol 655 ◽  
pp. 139-155
Author(s):  
DC Yates ◽  
SI Lonhart ◽  
SL Hamilton
Keyword(s):  
Species Interactions ◽  
Size Structure ◽  
Marine Reserves ◽  
Mortality Rates ◽  
Kelp Forests ◽  
Negative Effects ◽  
Central California ◽  
Invertebrate Predators ◽  
Predatory Fishes ◽  
Density And Biomass

Marine reserves are often designed to increase density, biomass, size structure, and biodiversity by prohibiting extractive activities. However, the recovery of predators following the establishment of marine reserves and the consequent cessation of fishing may have indirect negative effects on prey populations by increasing prey mortality. We coupled field surveys with empirical predation assays (i.e. tethering experiments) inside and outside of 3 no-take marine reserves in kelp forests along the central California coast to quantify the strength of interactions between predatory fishes and their crustacean prey. Results indicated elevated densities and biomass of invertebrate predators inside marine reserves compared to nearby fished sites, but no significant differences in prey densities. The increased abundance of predators inside marine reserves translated to a significant increase in mortality of 2 species of decapod crustaceans, the dock shrimp Pandalus danae and the cryptic kelp crab Pugettia richii, in tethering experiments. Shrimp mortality rates were 4.6 times greater, while crab mortality rates were 7 times greater inside reserves. For both prey species, the time to 50% mortality was negatively associated with the density and biomass of invertebrate predators (i.e. higher mortality rates where predators were more abundant). Video analyses indicated that macro-invertivore fishes arrived 2 times faster to tethering arrays at sites inside marine reserves and began attacking tethered prey more rapidly. The results indicate that marine reserves can have direct and indirect effects on predators and their prey, respectively, and highlight the importance of considering species interactions in making management decisions.

Persistence of giants: population dynamics of the limpet Scutellastra laticostata on rocky shores in Western Australia

2020 ◽  
Vol 646 ◽  
pp. 79-92
Author(s):  
RE Scheibling ◽  
R Black
Keyword(s):  
Population Dynamics ◽  
Western Australia ◽  
Size Structure ◽  
Survival Rates ◽  
Maximum Size ◽  
High Rate ◽  
Adult Survival ◽  
Rocky Shores ◽  
Adult Size ◽  
Decadal Time Scale

Population dynamics and life history traits of the ‘giant’ limpet Scutellastra laticostata on intertidal limestone platforms at Rottnest Island, Western Australia, were recorded by interannual (January/February) monitoring of limpet density and size structure, and relocation of marked individuals, at 3 locations over periods of 13-16 yr between 1993 and 2020. Limpet densities ranged from 4 to 9 ind. m-2 on wave-swept seaward margins of platforms at 2 locations and on a rocky notch at the landward margin of the platform at a third. Juvenile recruits (25-55 mm shell length) were present each year, usually at low densities (<1 m-2), but localized pulses of recruitment occurred in some years. Annual survival rates of marked limpets varied among sites and cohorts, ranging from 0.42 yr-1 at the notch to 0.79 and 0.87 yr-1 on the platforms. A mass mortality of limpets on the platforms occurred in 2003, likely mediated by thermal stress during daytime low tides, coincident with high air temperatures and calm seas. Juveniles grew rapidly to adult size within 2 yr. Asymptotic size (L∞, von Bertalanffy growth model) ranged from 89 to 97 mm, and maximum size from 100 to 113 mm, on platforms. Growth rate and maximum size were lower on the notch. Our empirical observations and simulation models suggest that these populations are relatively stable on a decadal time scale. The frequency and magnitude of recruitment pulses and high rate of adult survival provide considerable inertia, enabling persistence of these populations in the face of sporadic climatic extremes.

Causes of ecosystem transformations variability in lakes of the european part of Russia and Western Siberia (diatom analysis)

2019 ◽  
pp. 79-82
Author(s):  
Lev V. Razumovsky
Keyword(s):  
Western Siberia ◽  
Graphical Analysis ◽  
European Part ◽  
Analysis Method ◽  
Climatic Region ◽  
Diatom Analysis ◽  
Lake Ecosystems ◽  
Distinctive Features ◽  
European Part Of Russia

On the basis of author's graphical analysis method, the typification of lake ecosystems transformation scenarios depending on the size of lakes was carried out. It was confirmed that the type of transformation depends not only on size of the lake, but also on the landscape and climatic region in which it is located. The distinctive features of lake ecosystems transformation types in the European part of Russia and in Western Siberia were analyzed and compared.

Within year representativity of fish assemblage surveys in two small lowland streams

2012 ◽  
Vol 61 (2) ◽  
pp. 97-105 ◽  
Author(s):  
Péter Takács ◽  
Péter Sály ◽  
András Specziár ◽  
Péter Bíró ◽  
Tibor Erős
Keyword(s):  
Fish Assemblage ◽  
Lowland Streams
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