Reproduction, movements, and population dynamics of the southern kingfish, Menticirrhus americanus, in the northwestern Gulf of Mexico

Menlicirrhus americanus in the northwestern Gulf of Mexico mature at 150-220 mm TL and 12-14 months of age, with males maturing when 10-40 mm smaller than females. Spawning occurs within a broad period from February through November with two discrete peaks which coincide with the periodicity of downcoast alongshore currents (towards Mexico) in spring and fall. This species occurs at depths of less than 5 to 27 m, being most abundant at 5 m or shallower. Young-of-the-year recruit primarily at 5-9 m or shallower and gradually expand their bathymetric range. Age determination by length frequency is feasible in M. americanus but not as simple as in species that spawn in one major period of the year. Only one or two spawned groups normally predominated at anyone time and no more than three co-occurred with few possible exceptions. Observed mean sizes were 138 mm TL at 6 months, and 192 and 272 mm at ages I and II, respectively. Typical maximum size was 296-308 mm and typical maximum age is probably 2-3 years. The largest fISh captured were 392 and 455 mm. Observed sex ratio was 1.2 females to 1 male. Weight, girth, and length-length regressions are presented.(PDF file contains 27 pages.

A historical review of the shad fisheries of North America

A review of the relative productivity and value of the shad fisheries of North America as reflected in recorded commercial catches. A review of reasons for the decline that are biological and socioeconomic. Factors that have been held responsible are: pollution; destruction or impairment of spawning and nursery areas; overfishing; hydroelectric and canal dams; natural fluctuations in abundance. Natural catastrophes, parasites, and predators are not considered important in causing the decrease in commercial production. Attempts to rehabilitate the fisheries by various means of stocking artificially-reared fry and pond-reared fingerling shad, appear to have failed in every instance. Introduction of shad fry on the Pacific Coast has resulted in a major fishery. The most significant program is a controlled catch management plan, operating at this time [1953] only in Maryland

The vertical cloud structure of the West African monsoon: a 4 year climatology using CloudSat and CALIPSO

The West African summer monsoon (WAM) is an important driver of the global climate and locally provides most of the annual rainfall. A solid climatological knowledge of the complex vertical cloud structure is invaluable to forecasters and modelers to improve the understanding of the WAM. In this paper, 4 years of data from the CloudSat profiling radar and CALIPSO are used to create a composite zonal mean vertical cloud and precipitation structure for the WAM. For the first time, the near-coincident vertical radar and lidar profiles allow for the identification of individual cloud types from optically thin cirrus and shallow cumulus to congestus and deep convection. A clear diurnal signal in zonal mean cloud structure is observed for the WAM, with deep convective activity enhanced at night producing extensive anvil and cirrus, while daytime observations show more shallow cloud and congestus. A layer of altocumulus is frequently observed over the Sahara at night and day, extending southward to the coastline, and the majority of this cloud is shown to contain supercooled liquid in the top. The occurrence of deep convective systems and congestus in relation to the position of the African easterly jet is studied, but only the daytime cumulonimbus distribution indicates some influence of the jet position

Passive tracers in a general circulation model of the Southern Ocean

Passive tracers are used in an o?-line version of the United Kingdom Fine Resolution Antarctic Model (FRAM) to highlight features of the circulation and provide information on the inter-ocean exchange of water masses. The use of passive tracers allows a picture to be built up of the deep circulation which is not readily apparent from examination of the velocity or density ®elds. Comparison of observations with FRAM results gives good agreement for many features of the Southern Ocean circulation. Tracer distributions are consistent with the concept of a global ``conveyor belt'' with a return path via the Agulhas retro¯ection region for the replenishment of North Atlantic Deep Water

Pieces of eight, pieces of eight: seafarers’ earnings and the venture economy of early modern seafaring

Historians have generally argued that between the medieval period and the eighteenth century seafarers transformed from collaborative adventurers with a share in their vessel to the first international wage-earning proletariat. This interpretation has drawn upon relatively limited statistical analysis of mariners’ wages, and underestimates the variety of seafarers’ remuneration and economic activities besides wages themselves. This article undertakes a more sustained analysis of seventeenth-century wage data drawn from the papers of the English High Court of Admiralty, and uses the same evidence to examine other forms of income, both customary payments as part of shipping, and small-scale trade. Seafarers of all ranks carried their own commodities on all shipping routes, offering an opportunity to considerably increase their income. This evidence confirms that the maritime labour market was hierarchical, and that very often seafarers were poor labourers facing economic insecurity of many kinds. However, it refines the previous interpretation by emphasizing the presence of skilled workers even amongst the lower levels of this labour market, and by introducing a new dimension to mariners’ economic agency: they were not simply wage-workers, but also independent participants in a venture economy

Ground-water resources of the lower Hillsboro Canal area, Southeastern Florida

This study was done to determine the amount and kinds of water being produced from the lower Hillsboro Canal Area in Palm Beach and Broward counties. All of the potable ground water being produced from the Biscayne aquifer is developed from the canal through infiltration. Rainfall in the area is the ultimate source for all of the water. Careful control and management will allow the development of large quantities of water from the canal toward Lake Okeechobee, but a fresh water head must be maintained along the contact of fresh water with sea water to prevent salt water intrusion. (PDF contains 51 pages.

Synoptic review of the Literature on the southern oyster drill Thais haemastoma floridana

This literature search identifies a majority of the publications in the period 1880-1980 concerned with the marine gastropod, Thais haemastomafloridmul (Conrad). The southern oyster drill is an economically important oyster predator in the western Atlantic and Gulf of Mexico littoral. Major contributions of each paper to our knowledge of the drill's biology are briefly categorized. Hitherto unpublished research by the author on the snail's biology is documented. (PDF file contains 15 pages.

Realistic caution and ambivalent optimism: US intelligence assessments and war preparations against Japan, 1918-1941

Throughout the years prior to the outbreak of the Pacific War, the United States defence establishment held an ambiguous view on Japanese policy and strategic aims. A number of factors precluded a clear-cut forecast, among the most important of which was the opportunistic and secretive manner in which Japanese leaders formulated their plans. Under the circumstances, the available intelligence could not provide a definite indication of the moves which the Imperial Japanese Navy (IJN) and Imperial Japanese Army (IJA) would undertake. The situation was further complicated because reliable pieces of evidence revealed Japan did not possess the military and economic resources to defeat a coalition of several Great Powers. The Americans were thus not inclined to expect the Imperial forces to undertake a full-scale conquest of the Asia–Pacific region. The inadequate knowledge of Japanese war plans, in turn, was one of the key factors which led United States defence officials to believe that efforts to bolster their military strength in the Far East were not necessary