Methods of Surveying Laminaria Beds

Extract

Previous methods of survey by American workers are described and the differences between the species of seaweed involved are emphasized. The small stature of the European kelps renders all methods of survey difficult and the results can only be described as the best approximations. The British survey was divided into (1) a preliminary survey in order to determine the regions with the biggest beds, and (2) a detailed survey, when some of these major beds were mapped in detail. The primary survey was a rapid affair and the results were based on information obtained from (a) use of boat and grapnel, (b) existence of cast weed, (c) lobster fishermen, (d) coastguards, fishery officers, borough surveyors, harbour-masters, (e) inspection from cliffs, (f) a study of Admiralty Charts.

In the section on the detailed survey the different types of grapnel employed and also the method of using the box sextant are described. The use of an echo-sounder to locate weed beds is discussed and the different types of record obtained over various types of bottom or weed are noted. The use of a viewbox and personal observation is also mentioned, and finally an account is given of aerial photography as a means of survey. The most suitable conditions for success are noted and also the technique of interpretation for both oblique and vertical photographs. The plotting of these two types of photograph is described in some detail.