und nvater /SSN 0/41 0814. /nternationaIJourna/ ofthe Society for Underwater Techno/ag)!, Vol26, Na 2, pp 51-55, 2005 TECHNOLOGV

Trends in : an analysis of scientific -ca C.) diving operation records, 1970-2004 .-e J: C.) ~ MD] SAYER and] BARRINGTON UK Natiollal Faciliry Jor Scienlific Divillg, Scottish AssocialiollJor Marille Science, Dunstqffizage Marine Lahoralo1)\ Ohan, UK

Abstract As with any professional activity, understanding the risks assoeiated with operations tllat are pereeived a~ haz- A detailed trend analysis was made of 8611 scientific ardous can inform an employer's approach to sclf regula- diving operation records undertaken at the tion, can influence centralised government approaches to Dunstaffnage Marine Laboratory between 1970 and regulating potentially dangerous professional activities, 2004. The analysis represented 15 711 separate per- and can inform insuring bodies.7 Within the UK Diving son dives and a total of 285512 minutes of diving time. Industry obtaining good quality information for the dif- Specific trends were highly influenced by predominant ferent sectors is diffieult as fe"'~if any, maintain eomplete project areas during specific periods of the analysis. datasets from their members. Based largcly on informed However, most diving was relatively shallow with only estimates the risks associated with diving within speeifie 0-12% of annual dive duration at depths of 30m or sectors show considerablc variance.7 Obtaining realistic or greater, and the majority (32-87%) being in the 10-29m accurate analyses of risk by sector may be benefieial in depth range. Diving was undertaken throughout the either identifYing pOOl' diving praetiees 01', if good, tllen year and average dive depth and duration were not obtaining more preferablc insurance premiums on a sec- influenced by month. One incident of ill- tor by sector basis. ness (DCI) occurred within the dives analysed yielding a Records of all the diving operations undertaken at DCI incidence rate of 0.12 per 1000 dives or 0.06 per the Dunstaffnage Marine Laboratory have been main- 1000 person dives. This level of incident is within the tained and archived from the ineeption of the Diving Unit range for previous studies on (0.07-0.14) in 1970 and are analysed here to the end of 2004. but below reported incident rates for wreck and/or Analysis of these records offers the opportunity of profIl- multi-day (0.25-0.49). However, it is ing tlle type of diving undertaken by a scientifie institution suggested that true inter-sector comparisons of esti- in addition to analysing tlle safety record of such a faciJity. mated risk to the individual diver can only be made when expressing DCI rates in relation to person dives. 2. Materials and methods Average numbers of divers per dive in 'at work' opera- tions will usually be below two; some recreational dives The present analysis of diving trends at Dunstaflhage is may have many more than two divers per dive. based on diving operation records maintained between January 1970 and December 2004. During this period 1. Introduction tl1ere were a number of ehanges in tl1eguidance as to what information was required to be maintained as arecord of The UK Diving Industry is divided into five major sec- a diving operation. However, each of the records analysed tors where the divers are at work. I These are offshore for tlns study contained at least: tlle names of the divers diving operations mainly concerned with the support of involved in the diving operation, tl1e maximum deptll of commercial hydrocarbon extraction,2 the inland! tl1e dive undertaken and the total time for tlle dive. All inshore sector acting in support of civil engineering or depths initially measured in feet were converted to metrcs. shell fishing activities/ the media sector which covers All tl1e diving operation records were convertcd to professional photography or film making,4 the recre- person-dives dependent on the number of divers ational sector covering professional training of recre- employed for each operation. The maximum dcpth and ational divers,' and the scientific and archaeological sec- tl1e total duration for the dives were collated by montll tor employed in the pursuit of scientific 01' archaeolog- and year. The dive durations were also collated by month

1 ical reward. ; In addition to these five major sectors, div- and year depending on the ma..ximum depth reached and ing in the UK is dominated numerically by amateur allocated to four deptl1 ranges (0-9m, 10-19m, 20-29m leisure divers. There are also significant diving opera- and 30m 01' greater). The number of person dives, total tions undertaken by the police and the armed , dive duration, average maximum depth, and average dive who, although 'at work', are classified differently to the duration were all calculated botl1 by montll and by yeal: other sectors. The depth distributions were calculated by year only.

51 Sayer & Barrington. Trends in scientific diving

1800.0 3. Results w- .!: 1600.0 E total :;;- 1400.0 A of 8611 diving operation records were inc1uded i: ~ 12000 in the analysis representing 15 711 separate person ~ dives and a total of 258 812 minutes of diving time. .,~ 1000.0 Over the whole period, the average number of person .,E., 800.0 > 600.0 dives per month was 37.6 (range of 0 to 142: n=420), '6., with the levels being slightly greater during the summer Ol 400.0 ~•• months (May to August) and lower during the winter ~ 200.0 ones (October to March: Fig I). Over the total period 0.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec tl1erewere some obvious interannual trends in monthly Month averages with higher levels from 1970 to 1983, 10wer Fig 3: The average (± 1sd) total dive time (mins) by levels from 1983 to 1992, and levels approximating to month undertaken at Dunstaffnage between 1970- average from 1992 to 2004 (Fig 2). 2004. The dashed horizontal line represents the dive The trend in average total time underwater per time per month averaged for the total study period montl1 was similar to tl1efigures for average number of .c 3000 total E person dives per month. The average monthly dive o time over the whole period was 679.8 minutes (range 0 ~ 2500 to 3851; n=420) witl1 tl1e trend for longer summer a. ~ 2000 cumulative levelscompared with the winter months, and ., ~'iiJ witl1 higher levels in the 1970s and early 1980s com- '6.!: 1500 '6'.E. lJl 80 ::: 1000 .;t. lJl ., ., 70 > ~ 500 '6 ., 5 60 ~ ~ ~ 50 Ö Year t 40 .<:1 § 30 Fig 4: The average (± 1sd) monthly dive time (mins) by .,c year undertaken at Dunstaffnage between 1970-2004. ~., 20 ~ 10 The dashed horizontalline represents the dive time per month averaged for the total study period ~ ~b Mar ~r M~ Jun Jul ~g ~p ~ ~ ~ Month pared with post-1982 (Figs 3 and 4, respectively). Fig 1: The average (± 1sd) number of person dives per With the total durations and numbers of dives per month by month undertaken at Dunstaffnage between month following similar trends, it would be expected 1970-2004. The dashed horizontalline represents the that dive duration would remain similar throughout number of person dives per month averaged for the the study period. The average dive duration was 31.9 total study period minutes (range of monthly averages was 13.5 to 70.5; n=420) and monthly durations deviated little from Fig 2: The average (± 1sd) person dives per month by year the overall mean (Fig 5). However, when examined undertaken at Dunstaffnage between 1970-2004. The by year, dive durations were consistently above aver- dashed horizontalline represents the number of person age during the period 1972 to 1980 and mostly bclow dives per month averaged for the total study period average after that (Fig 6). The average maximum dive 120 .c depths ranged from 3.3 to 35.8m i: 110 o (n=420) with an overall monthly e 100 average of 13.3m (n=420); there was ~ 90 no obvious monthly trend (Fig 7). .~8l 80 "'Cl c 70 Maximum deptl1sper year remained .,~ 60 elose to tl1e overall average, apart ;: 50 from the periods 1970-1971 (abovc lJl ":' 40 average) and 1973-1975 (belowaver- 130 ., age; Fig 8). Although tl1e average i' 20 ~ 10 maXImum depth varied littlc o throughout the recording period, when expressed in terms of tl1e div-

52 und rwat r TECHNOLOGY 'VoI26, No 2, 2005

ing duration at depth, 31.9% of the diving was in the 0- but was Iess than 20% for 11 out of the 19 years far the 9m range, 56.4% was between 10 and 19m, 9.6% in the period 1986-2004 (Fig 9). This decline was mostly made 20-29m range, and 2.1% in 30m 01' greater. However, this up by an increase in the proportion of diving undertaken distribution changed throughout the study period most in the 10-19m depth range, which accounted [01' 1essthan markedly for the 0-9m range which accounted for over 40% of the total dive duration for the period 1973-1975 60% of the total dive duration far the period 1973-1975 but was greater than 60% for 14 out of the 19 years for

60.0 30 lii' _ 55.0 l!! Gi 25 .~'" 50.0 §. J: ~ 45.0 o i 20 ., "0 ~ 40.0 " 15 "0" 35.0 :6 > '6' 'ö" 30.0 ~'" 10 "g> 25.0 .:!:. ~ 20.0 " 4( E 5 15.0 ~ 4( 10.0 Jen Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dee

Month Year

Fig 5: The average (±1sd) dive duration (mins) by Fig 8: The average (± 1sd) maximum dive depth per month undertaken at Dunstaffnage between 1970- month (metres) by year undertaken at Dunstaffnage 2004. The dashed horizontalline represents the between 1970- 2004. The dashed horizontal line average dive duration for the total study period represents the maximum dive depth averaged for the total study period _ BO '"c ~ ~100 ~ 70 c c .~ 900 .g 60 E ~ 800 -6 50 'tl" 70.0 Cl > c: :a" 40 .;; '6' '6 500 ~ 30 19 40.0 ':j: o -; 20 -; 300 Cl Cl ~ 20.0 ~ 10 > ~ 10.0 4( u :D 0.0 Q. ~ ~ ~ ~ ~ ~ N ~'" ~ ~ 2 ~ ~ ~ ~ ~ N8~ ~ m m ~ ~ ~ ! _! ! ~~~~~~N ~ Year Year Fig 16: The average (± 1sd) dive duration per month (mins) by year undertaken at Dunstaffnage between Fig 9: Percentage of the total diving duration (mins) by 1970- 2004. The dashed horizontalline represents the depth range undertaken at Dunstaffnage between average dive duration for the total study period 1970- 2004

o---c: yearly percentage; ----: 5 year rolling average; -: 10 year rolling average;

20.0 90.0

1B.0 ~ 80.0 c I 16.0 ;; .2 Q. E 70.0 ~ 14.0 'tl" ...... , .L': -~ ~ ,..:: - - -- .5 60.0 ~ '"> :a 12.0 'ö Cl " ~ 50.0 '":;; 10.0 ~ S'"" 40.0 8.0 c "e :. 30.0 6.0 Jen Feb Mar Apr May Jun Jul Aug Sep Det Nov Dac Month 20.0

Fig 7: The average (± 1sd) maximum dive depth (metres) Year by month undertaken at Dunstaffnage between 1970 and Fig 10: Percentage of the total diving duration in the 2004. The dashed horizontalline represents the average 10-29m depth range undertaken at Dunstaffnage maximum dive depth for the total study period between 1970-2004.

53 Sayer & Barrington. Trends in scientific diving

the peliod ]986-2004 (Fig 9). The 20-29m depth range weed research, average dive durations tended to be eontlibuted to over ]0% of the total duration within the higher. From] 991 to 2001, most diving activity con- periods 1979-1985 and ]994-2002 but significant centrated on inshore fish surveys.12,]3, 14 The fish survey amOllnts of diving at depths of 30m or greater were only dives tendecl to be on fixed transects of standard recorded in the first 1:\voyears of operation (1970 and lengths, swam over standardised durations and as a con- 1971; Fig 9). The increases in durations in the 10-19m sequence average annual depths and durations showeel and 20-29m depth ranges "vitha coneomitant decrease in little deviation [rom the ranges o[ 14 to 16m depth for durations in the 0-9m range reslllted in the proportion of 25-30 minutes duration during this period. diving being llndertaken within the 10-29m depth range Over the total period of this analysis there has been a increasing from below 40% in the mid-1970s to over 80% general shift in the methods in which scientificresearch is fium 2000 onwards (Fig 10). structured anel supported at Dunstaffnage anel scientific No [atalities occurred during the period of study. diving has become less integrated with large-scale strate- One case o[ (DCI) was recorded gie research projects anel is more elependent on eommis- throllghollt the period of study. Expressed as a ratio of sioned research projects. As a consequence of this, there the total number of diving operations the DCI ineident were periods when research projects involving cliving level was 1:8611. Expressed as a ratio of the total num- were less numerous whieh caused a eoncomitant decline bel' of person dives the incidence of DCI was 1:15 711. in di\~ng activity (eg, 1988-1991). The percentage incidence of DCI [or the whole period Seawater at Dunstaffnage tend to reach was 0.012% (0.12 incidents per 1000 dives) and 0.006% their minima (ca 5°G)in February/March and their max- l (0.06 incidents per 1000 person dives) for dives and per- ima (ca 15°C)in August/September. wreck diving;190.29-0.33 20 of underwater science have dominated the di\~ng sup- for mlllti-dive multi-day holiday / conference diving ). port effort. From 1970 to 1971 average annual depths In the present study, the DCI incidence rate falls to were be1:\veen18 and 23m. This coincided with research 0.06 when expressed as a proportion of 1000 person focussed on deepwater bentllic macrofauna.8,9,10During dives. Previous studies have used a variety of units to the period 1973-1975, average depths were shallower express the rates of DCI incidence. Some have used than 10m which was aperiod when di\~ng projects were the number of bottle fillslogged in a particular region,IH predominated by research on seaweeds that only occur others simply use the number of diving operations or 16 in shallow water.11Dive duration "villalways tend to be dives. 17,, 19The present study uses person dives as this influenced by depth, and during the period of most sea- gives a more accurate estimate of risk to the individual und rwat r TECHNOlOGY Vol 26, No 2, 2005 divcr. Therc are diffcrences in how a unit diving oper- 6. Scientific and archaeological diving projects (Diving ation equates to person dives for the different sectors of at Work Regulations 1997): Approved Code of the diving industry. In sectors where surface supply div- Practice. NOIVVich;HSE Books 1998: LI07: 26pp. ing is prevalent, consisting mainly of a single diver in 7. PARAS (1996). SCUBA diving: A quantitative risk the water with a stand by diver at the surface, the ratio assessment. HSE contract research report 140/1997. of diving operations to person dives will tend toward a 8. Gage]. (1972). A preliminary survey of the benthis value of one. In the recreational sector, single diver div- macrofauna and sediments in Lochs Etive and ing is large1y avoided and the ratio of dives to person Creran, sea lochs along the west coast of Scodand. dives will rare1y be Iess than two and could be regularly Journal qf tIze Marine Biological Association qf tIze Uni/cd ten 01' above in deal' water operations. Kingdom. 52: 237-276. In order to make meaningful inter-sector compar- 9. Gage]. (1972). Community structure of the benthos isons of the DCI risk to the individual diver, then report- in Scottish sea lochs. 1. Introduction and species ing should standardise on an incidence rate per unit diversity. . 14: 281-297. number of person dives. Assuming a minimum conver- 10.Gage]. (1975). A comparison of the deep-sea epiben- sion factor of two person dives per dive for the recre- thic sledge and anchor-box dredge samplcs with the ational sector produces estimates of no more than 0.04 van Veen grab and hand coring by diver. Deep Sea DCI incidents per 1000 person divesfor leisure diving,16.17 Research. 22: 693-702. although this could still be as high as 0.12 where bottle 11.Powell HT, Holme NA, Knight SJT, Harvey R, fillsshould equate doseIy to person dives,IB01' 0.29-0.33 Bishop G and Bartrop]. (1980). Survey of the Et- where the number of 'dives' has been estimated from a toral zone of Great Britain: Report on the shores of simple multiplication based on diver numbers.20 north west Scotland. 5MBA/MBA Intertidal Survey Obtaining accurate assessments of diving trends Unit Report to the NCC, No 6. and incident rates by diving industry sector permits 12.Sayer J\IDJ, Gibson RN and Atkinson RJA. (1993). detailed analyses of risk to be made by managers, regu- Distribution and density of populations of goldsinny lators, individuals and insurers alike. 'i\Thereas most ,·vrasse(Ctenolabms mpestris) on d1ewestcoastof Scodand. previous analyses have required degrees of assumption Journal qf Fish Biology. 43: (SupplementA), 157-167. or estimate,16.17.IB.20 the present analysis is an exact 13.Magill SH and Sayer MD]. (2002). Seasonal and assessment of over 285 000 minutes of diving that have interannual variation in fish assemblages of north- becn logged accurately. Similar analyses of diving em temperate rocky subtidal habitats. Journal qf Fish trends over comparable scales of study period and dive Biology. 61: 1198-1216. number would permit precise comparisons to be made 14.Magill SH and Sayer MD]. (2004). Abundance of between the various sectors. juvenile cod (Gadus morhua) in the shallow rocky sub- tidal and the relationship to winter sea\vater temper- Acknowledgement ature. Journal qf the Marine Biological Association qf the United Kingdom. 84: 439-442. The authors acknowledge support for this study from the 15.ArnessMK. (1997). SCUBA decompressionillnessand National Environment Research Council (NERC) through diving fatalities in an overseas military community. funding for the UK National Facilityfor ScientificDiving. Aviation, Space and Erwironmental Mediane. 68: 325-333. 16.Wilmshurst P, Allen C and Parish 1'. (1994). References Incidence of decompression illness in amateur SCUBA divers. Health 'Trends. 26: 116-118. I. Sayer M. (2004). Assessing and managing risk in 17.Gilliam B. (1992). Evaluation of decompression UK scientific diving at work operations. Journal qf sickness incidence in multi-day repetitive diving for the South Pacific Underwater Medicine Sociery. 34: 81-88. 77 680 sport dives. Journal qf the South Pacific 2. Commercial diving projects offshore (Diving at Underwater Medicine Sociery. 22: 24-30. Work Regulations 1997): Approved Code of 18.Ladd G, Stepan V and Stevens L. (2002).The Abacus Practice. Norwich; HSE Books 1998: LI07: 26pp. Project: establishing the risk of recreational SCUBA 3. Commercial diving projects inlandlinshore (Diving death and decompression illness.Journal qf the South at Work Regulations 1997): Approved Code of Pacific Underwater Medicine Sociery. 32: 124-128. Practice. Norwich; HSE Books 1998: LI 07: 26pp. 19.Trevett AJ, Forbes R, Rae CK, Sheehan C, Ross.J, 4. projects (Diving at Work Regulations Watt S.Jand Stephenson R. (2001). Diving accidents 1997): Approved . Norwich; HSE in sports divers in Orkney waters. Scottish Medical Books 1998: LI 06: 34pp. Journal. 46: 176-177. 5. Recreational diving projects (Diving at Work 20.Davis M and Williams R. (2003). Decompression ill- Regulations 1997): Approved Code of Practice. ness in a tropical resort. Journal qf the South Pacific Norwich; HSE Books 1998: LI07: 34pp. Underwater Medicine Sociery. 33: 46-48.

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