OSG Circular Memorandum No. 1-1994

‚ÄčNOTE: This circular has subsequently been edited to reflect an amendment to the Living Marine Resources Management Act 1995, effective from September 2007, that changed the coordination requirement for marine farm leases from AMG to MGA coordinates.

18 February, 1994


Surveyors role: New leases or permits
Surveyors role: Variation to existing leases and permit
Surveyors role: Marine Farm boundary interpretation
Surveyors' responsibility and accountability
Technical considerations
Special survey and boundary requirements

Surveyors' Role & Survey Requirements - Marine Farm Boundaries


During the latter part of 1992 the Director of Sea Fisheries, in consultation with the Surveyor General, decided to adopt a totally new approach to the definition and description of marine farm boundaries. As a consequence of this decision, the boundaries of any area in respect to which a marine farm lease, re-seeding lease, or permit is to be issued, will in future, be defined in absolute terms as a co-ordinated polygon on the Australian Map Grid (AMG) Map Grid of Australia (MGA).

In the case of those existing marine farms where no accurate boundaries have previously been established in lease or permit documents, the Director of Sea Fisheries has recently written to the established marine farmers requesting that they arrange for surveys of their existing tenancies to be carried out within 90 days, in order that existing leases or permits may be reviewed and re-issued in accordance with the new system. A number of survey firms have already been approached in regard to the execution of the required survey work.

In carrying out any survey work associated with this new form of boundary, it is vital that all surveyors fully understand the technical and professional implications of the decision to adopt AMG MGA co-ordinated polygons to define the boundaries, as distinct from the traditional concept of survey boundaries defined by ground monuments and supported by documentation of the spatial relativity between the boundaries and supporting physical evidence.

In simple terms, the traditionally accepted hierarchy of boundary evidence will be completely reversed, with boundary points being re-established as necessary from the prescribed AMG MGA co-ordinates. Physical boundary monuments, together with evidence of occupation, will remain at best merely indicative of the true boundary position.

Surveyors role: New leases or permits

The task of the surveyor will be to carry out whatever survey work may be necessary to allow the prescription of an AMG MGA co-ordinated polygon which, when translated or projected in absolute terms as a series of ground point positions, would safely contain all of the improvements and activities of the lessee or permit holder.

It must be understood that, in a legal sense, the survey will not itself define the future boundaries of the subject lease or permit. The survey will simply provide the Director of Sea Fisheries with essential spatial information, which will subsequently be utilised in the definition of the new boundaries by co-ordinates.

There can be no standard specifications for this type of survey. In the case of a large and isolated marine farm in relatively exposed waters, aerial photography and large scale mapping might well provide a sufficient basis for prescription of the required boundaries. However, in the very different circumstances where a number of small adjacent leases might be situated in close proximity to the shoreline, a survey yielding relatively high positional accuracy will be needed, with great care being essential in the selection of the control points to provide AMG MGA co-ordinate datum and in the execution of the AMG MGA connections.

Regardless however of the particular nature of the farm under survey, it must be noted that any technical survey error, particularly when associated with the AMG MGA connections or datum could have extremely serious implications.

New lease and permit diagrams will in all cases be prepared by the Office of the Surveyor General (OSG); submitted for approval by the Director of Sea Fisheries and, following approval, registered in the Central Plan Office. In addition, every new or amended lease or permit area, will be spatially represented with absolute numerical co-ordinate precision, in a Marine Farm Tenancies layer established within the Department's integrated spatial information system.

Surveyors role: Variation to existing leases and permits

In the case of existing farms, where a survey has been required by the Director of Sea Fisheries for the purpose of establishing the boundaries of the area to which occupation authority has previously been granted, it may well be established that the previously documented lease or permit area does not coincide with the area now occupied.

In these circumstances, the task of the surveyor will be to very carefully examine the existing lease or permit documentation; and to carry out whatever survey work may be necessary to enable an area, the location, size and shape of which is consistent with that originally granted, to be accurately and unambiguously defined by AMG MGA co-ordinates in a new format lease or permit.

Some farmers may wish to apply for additional farm areas, either because of intended expansion, or in an attempt to regularise their present occupation where it exceeds the area to which they are entitled. The survey should, in such cases, provide all of the information necessary to allow definition of both the new and original areas in the format required under the new system of marine boundaries.

Surveyors role: Marine Farm boundary interpretation

As a consequence of the adoption of the new form of boundary definition, surveyors will at times be required to carry out surveys to confirm that marine farming activities, nominally within a lease or permit area, are in fact located within the confines of the ground projection of the AMG MGA co-ordinated polygon which defines, in absolute terms, the legal extent of the marine farm. Similar surveys may also be required to check or replace poles, buoys or other forms of operational, as distinct from legal, boundary markers.

In carrying out a survey to establish the spatial relationship between the legal boundaries of a marine farm and any structures or activities reputedly within it, surveyors should note that the simple re-establishment of a preceding survey may not necessarily provide an acceptable result. The possibility of a previously undetected error having occurred, particularly in earlier AMG MGA connections, cannot be ignored; any such error could have resulted in part, or all, of the operational farm being incorrectly located outside the legal boundaries.

Survey notes and other documentation associated with the ground interpretation of established marine farm boundaries should also be lodged in the OSG, where they will be retained with previous survey records associated with the subject marine farm.

Surveyors' responsibility and accountability

Surveyors must recognise that in carrying out marine farm surveys, they will be working outside the prescriptive, albeit protective, environment of normal regulated survey procedures. Surveyors will have a professional duty of care to their client to:
  • Accurately assess and advise as to what absolute co-ordinate accuracy needs to be achieved in point fixation, in each particular circumstance;
  • Identify the range of survey technology and procedures potentially capable of delivering the required survey outcome, and provide recommendations as to the most appropriate options; and
  • Carry out the survey, utilising such checking procedures and redundancies as may be necessary to adequately safeguard their own, and their clients, interests.

Technical considerations

The question of what instrumentation, survey techniques or reference monuments are to be utilised will remain a matter for the surveyor to decide in each individual case. These decisions must be reached on the basis of the surveyor's specialist technical expertise in surveying and position determination, having prudent regard to the following factors:
  • The positional error inherent in the quoted co-ordinates of the control points which are to be adopted as a basis for the establishment of AMG MGA co-ordinate datum;
  • The cumulative error potential, inherent in the selected survey and connection process;
  • The relative proximity of other potentially conflicting tenancies;
  • The level of positional uncertainty which the client may be prepared to accept safeguarding his assets, and his future operations;
  • An awareness that no matter what survey techniques and instrumentation are adopt it will never be possible for any surveyor to establish the co-ordinates of any physical feature, or the ground position of any co-ordinated boundary point, without some positional error and uncertainty.

Special survey and boundary requirements

In carrying out surveys which are to provide the basis for the issue of a new lease or permit, surveyors should note the following points, and ensure that survey documentation lodged with the OSG will adequately support the prescription of new boundaries in the format specified:
  • Every marine farm area will be bounded by right lines, and defined as a co-ordinated polygon on the AMG MGA. Where a marine farm boundary purports to be located immediately adjacent to Mean Low Water Mark (LWM), a series of boundary corners are to be identified at or below LWM, such that the resulting series of connecting boundaries exclude any land above LWM.
  • Documentation of all surveys carried out for marine farm purposes, should include details of the AMG MGA control connections used, together with an estimate of the end point co-ordinate accuracy achieved. Documentation of all surveys carried out for marine farm purposes, should include co-ordinate fixation of any existing permanent or semi-permanent improvements located within the intended farm area.
  • In all normal circumstances, survey documentation should be submitted for lodgement in the OSG utilising the standard Survey Note forms. Special consideration will be given to the use of alternative documentation formats, where the survey has been carried out using GPS or alternative technology.
Any surveyor requiring further advice or assistance in relation to any aspect of marine farm surveys, is encouraged to direct his enquiries, in the first instance, to the Surveyor General.

C.M Rowe