Pacific herring, Clupea pallasi, studies and fishery management in Tomales Bay 1992-93, with notes on Humboldt Bay and Crescent City area landings

The 1992-93 spawning biomass estimate for Pacific herring, Clupea pallasi, in Tomales Bay increased for the fourth year in a row to 4,078 tons. This is the highest estimate since the 1986-87 season. The December spawning biomass total of 1,346 tons was the second highest December escapement total since surveys began in 1972-73. A total of 3.58 million m2 of eelgrass, Zostera marina, was measured in Tomales Bay this season. Eelgrass density increased in the majority of beds. The commercial catch of 222 tons was taken entirely from Tomales Bay since outer Bodega Bay was closed to herring fishing during the season. Gill net mesh size was increased to 2.125 inches from 2.0 inches this season. Herring aged 4,5, and 6 comprised 92% by number of the season's herring catch. Mean weight of herring for each age decreased while mean length for all ages combined increased slightly. Tomales Bay herring samples indicated that older year-classes, missing in commercial catch samples, were present prior to the January start of the commercial fishery. The abundance of 4-yr-old herring was low in samples from variable-mesh and commercial gill nets, indicating less than average recruitment of the 1989 year-class. In Humboldt Bay the 1992-93 season commercial herring catch totalled 28.6 tons, less than half of the 60-ton quota. Crescent City area herring fishermen nearly caught their 30-ton quota with a total of 28.5 tons landed. No spawning biomass estimate is available for the 1992-93 season for either area. (29pp.

Pacific herring, Clupea pallasi, studies and fishery management in Tomales Bay, 1993-94, with notes on Humbolt and Crescent City area landings

The 1993-94 spawning biomass estimate for Pacific herring, Clupea pallasi, in Tomales Bay declined 40% from last season to 2,449 tons. Although this estimate is below the 20-year average of 4,700 tons, the spawning biomass estimate this year is close to the post 1982 El Nino 11-year average of 2,054 tons. The overall trend of increasing biomass since the 1989-90 season still continues. There were eight distinct spawns this season, the most in five years, with the largest spawn occurring in late January. A total of 3.5 million m2 of eelgrass, Zostera marina, was measured in Tomales Bay this season. Eelgrass density increased in the majority of the beds. The commercial gillnet fleet in Tomales Bay caught a total of 219 tons of herring this season yielding an exploitation rate of 8.9%. Herring aged four, five, and six comprised 90% by number of this season's commercial gill net catch. Mean weight of herring ages three, six, and seven decreased slightly over last season while increases were seen for ages four, five, and eight. Mean length of commercial caught herring increased slightly over 1992-93. Department variable-mesh gill nets caught a total of 455 herring of which 232 were aged. The dominant age class was four-yr-olds comprising 27% of the sample by number, followed by six-yr-olds representing the highly successful 1988 year class. In Humboldt Bay, the 1993-94 commercial catch of 62.8 tons was about 5% over the 1993-94 season quota of 60 tons and was well above Humboldt Bay's 21-year average catch of 40.4 tons. Crescent City area herring fishermen caught 32.5 tons, approximately 2% over the season quota for the Crescent City area. The 1993-94 season commercial catch is well above the 20-year average of 23.7 tons for this area. (31pp.

Vacuum polarization by topological defects in de Sitter spacetime

In this paper we investigate the vacuum polarization effects associated with a massive quantum scalar field in de Sitter spacetime in the presence of gravitational topological defects. Specifically we calculate the vacuum expectation value of the field square, $$. Because this investigation has been developed in a pure de Sitter space, here we are mainly interested on the effects induced by the presence of the defects.Comment: Talk presented at the 1st. Mediterranean Conference on Classical and Quantum Gravity (MCCQG

Theory of the Fermi Arcs, the Pseudogap, TcT_c and the Anisotropy in k-space of Cuprate Superconductors

The appearance of the Fermi arcs or gapless regions at the nodes of the Fermi surface just above the critical temperature is described through self-consistent calculations in an electronic disordered medium. We develop a model for cuprate superconductors based on an array of Josephson junctions formed by grains of inhomogeneous electronic density derived from a phase separation transition. This approach provides physical insights to the most important properties of these materials like the pseudogap phase as forming by the onset of local (intragrain) superconducting amplitudes and the zero resistivity critical temperature $T_c$ due to phase coherence activated by Josephson coupling. The formation of the Fermi arcs and the dichotomy in k-space follows from the direction dependence of the junctions tunneling current on the d-wave symmetry on the $CuO_2$ planes. We show that this semi-phenomenological approach reproduces also the main future of the cuprates phase diagram.Comment: 5 pages 7 fig