Glossary: S

sample	INDEX
A proportion or a segment of a fish stock which is removed for study, and is assumed to be representative of the whole. The greater the effort, in terms of both numbers and magnitude of the samples, the greater the confidence that the information obtained is a true reflection of the status of a stock (level of abundance in terms of numbers or weight, age composition, etc.).

sea-bed and subsoil	INDEX
The "sea-bed and subsoil" is a geographical term frequently used in international conventions to refer to the floor of the seas and oceans and the submarine land mass. For legal purposes, there is no substantial difference between the terms "sea-bed" and "ocean floor" although in the 1970s the former was more frequently used by some in the context of the bottom of marginal, enclosed or semi-enclosed seas. It should also be noted that Article 1(1) of the LOS Convention defines those parts of the sea-bed and ocean floor and the subsoil thereof which are situated beyond the limits of national jurisdiction as the "Area."

sedentary species	INDEX
The definition of sedentary species and the determination of the legal regime governing their exploitation have traditionally been a problematic one in international law, leading to a number of conflicts between States, such as the 1968 "lobster war" between France and Brazil. Under the LOS Convention (Art. 77), coastal States are given sovereign rights to exploit sedentary species as part of the continental shelf regime. That same Article defines sedentary species as organisms which, at the harvestable stage, are either immobile on or under the sea-bed or are unable to move except in constant physical contact with the sea-bed or the sub-soil.

seine nets

INDEX

Seine nets are very long nets which are used to surround an area of water. Such nets are usually operated by two ropes fixed to its ends, used both for hauling it in and for herding the fish. They can be operated either from the shore (beach seines) or from a boat (e.g., Danish seines) but in both cases are usually set from a boat.
See also:

	Danish seines
	Purse seines
	Surrounding nets

spawning stock biomass (SSB)	INDEX
The total weight of all sexually mature fish in the population. This quantity depends on year class abundance, the exploitation pattern, the rate of growth, fishing and natural mortality rates, the onset of sexual maturity and environmental conditions.

spawning stock biomass-per-recruit (SSB/R)	INDEX
The expected lifetime contribution to the spawning stock biomass for a recruit of a specific age (e.g., per age 2 individual). For a given exploitation pattern, rate of growth, and natural mortality, an expected equilibrium value of SSB/R can be calculated for each level of F. A useful reference point is the level of SSB/R that would be realized if there were no fishing. This is a maximum value for SSB/R, and can be compared to levels of SSB/R generated under different rates of fishing.

stock	INDEX
A part of a fish population usually with a particular migration pattern, specific spawning grounds, and subject to a distinct fishery. A fish stock may be treated as a total or a spawning stock Total stock refers to both juveniles and adults, either in numbers or by weight, while spawning stock refers to the numbers or weight of individuals which are old enough to reproduce.

straddling stock	INDEX
Straddling stocks are stocks which occur both within and in an area beyond and adjacent to the economic or fishing zones of coastal States. The term is not actually used in the LOS Convention.

surplus production	INDEX
Production of new weight by a fishable stock, plus recruits added to it, less what is removed by natural mortality. This is usually estimated as the catch in a given year plus the increase in stock size (or less the decrease).

surrounding nets IMAGE	INDEX
These nets catch fish by surrounding them both from the sides and from underneath, thus preventing them from escaping in deep waters by diving downwards. Apart from a few exceptions, they are surface nets in which the floatline is supported by numerous floats. Examples include purse seines and lampara nets (surrounding nets without purse lines: see image).

survival rate	INDEX
Number of fish alive after a specified time interval, divided by the initial number. Usually on a yearly basis.

sustainable yield	INDEX
The number or weight of fish in a stock that can be taken by fishing without reducing the stock biomass from year to year, assuming that environmental conditions remain the same.