Cooperation in the face of thresholds, risk, and uncertainty: Experimental evidence in fisher communities from Colombia

Cooperation is thought to be a necessary condition to solve collective action dilemmas such as climate change or the sustainable use of common pool resources. Yet, it is poorly understood how situations pervaded by thresholds shape the behaviour of people facing collective dilemmas. Here we provide empirical evidence that resource users facing thresholds maintain on average cooperative behaviours in the sense of maximising their individual earnings while ensuring future group opportunities. A framed field experiment in the form of a dynamic game with 256 Colombian fishers helped us investigate individual behavioural responses to the existence of thresholds, risk and uncertainty. Thresholds made fishers extract less fish compared to situation without thresholds, but risk had a stronger effect on reducing individual fishing effort. Contrary to previous expectations, cooperation did not break down. If cooperation can be maintained in the face of thresholds, then communicating uncertainty is more policy-relevant than estimating precisely where tipping points lay in social-ecological systems.

and Yellow (1,2,3,4). Keep in mind that people from the same household (e.g., siblings, cousins)  On a different room: 133 Good morning / afternoon. My name is <your name here> and our assistant is <assistant name> and we will guide you 134 throughout the game. Now you are a group of 4 fishermen who share the same fishing ground with 50 fish. In front of 135 you, you will find a folder with your decision cards, calculators and a pen. If you need help writing or keeping the count, 136 please let us know, our assistant and me are here to help you.

137
Practice rounds 138 Before we start the first stage of the game we are going to do some practice rounds to make sure we all have understood 139 the instructions. Please note: you do not earn any money during the practice rounds. During the practice rounds we 140 do not reveal who took what, only what "someone took" and we will do the calculation of the stock size openly together 141 so that everyone can follow it. Now you have two minutes that you can use to discuss your decisions, after that time 142 you must write your decision and we will gather the decision folders. 143 <We pick up the decision cards and bring them to Caroline. She will return a paper with the individual catch on a 144 random order so you can read it publically. Use the bowl with the fake fish on the table, i.e., take out fish and then add 145 fish to the bowl accordingly> 146 Okay, during this practice some one caught <take out fish from the bowl as you read>, another person caught…, the 147 third person… and the last one…. <make sure to count how many fish is left in the bowl afterwards with the fishermen>. 148 Therefore, the fish stock is left with XX fish. So, how many fish will reproduce for the next round? If not, let's start the first stage of the game. -This means that from now on you will earn some money according to the decisions you make 154 In case you listen to other groups playing, you should know that what happens in other groups is not related to what 155 happen in our group game. Maybe they finish earlier, but that does not mean that the game you are participating will 156 also end. Before we start the first stage of the game for real, here is a short summary of the rules of the game:

157
• The four of you share together a fishing ground. 158 • In each round, you will take an individual and private decision of how many fish to catch. You can choose to fish 159 as much fish as there is available or not fishing at all (zero). For each fish you capture you earn 500 pesos. You 160 will also guess how many fish will be left in the stock for the next round.

161
• Your decisions affect your individual earnings but also the resource of the community.

162
• As long as there is fish left, this stage of the game continues and you can keep earning money. 163 • If the resource collapses, this stage of the game ends.

164
• We do not tell you how many rounds you will play. 165 • The fish reproduction depends on how much fish there is left on the fish stock <point to illustration and remind 166 them of the tables they got> 167 • You are not allowed to show each other what you write down on your decision cards. 168 • Remember, you are allowed to talk in the game. This means you can talk about whatever you want even of how 169 much you want to fish for a maximum of 2 minutes time between rounds. After the 2 minutes, you need to write 170 down your decision. The fish stock starts with 50 fish, now you have two minutes that you could use to discuss your decisions. After that 174 time you need to write your decision and we will pick up the decision folders. size, which is […<write down the stock size for next round>]. We also want to inform you that a climate event -with 188 long lasting and negative consequences for the fishing ground you manage in common might occur.

189
The climate event will affect the fish reproduction rate, it will decrease below fish stock size of 28 fish. As you can 190 see here <point out the new illustration with threshold dynamics>, the reproduction will only be of a fish for stock size 191 between 2 and 27 fish. For any other stock size, the reproduction rate will be the same, between 2834 it will be 10 192 fish, between 3545 it will be 5 fish, as you can see here<point out>. The stock size between 04 and between 4550 193 wont reproduce extra fish.

194
Thus, the climate event brings an abrupt reduction on the fish growth if the population size is 28 fish or less. <if 195 participants ask why: the climate event can reduce rain showers, increase water temperature and the risk of droughts. With this new information, we will also reestablish the population size back to 50 fish <here please strikethrough the 202 number of fish left last round of the first stage and clarify that the stock size starts again with 50 fish>, just as the 203 beginning of the game. All other rules remain the same:

204
• The four of you share together a fishing ground.

205
• In each round, you will take an individual and private decision of how many fish to catch. You can choose to fish 206 as much fish as there is available or not fishing at all (zero). For each fish you capture you earn 500 pesos. You 207 will also guess how many fish will be left in the stock for the next round.

208
• Your decisions affect your individual earnings but also the resource of the community.

209
• As long as there is fish left, this stage of the game continues and you can keep earning money. If the resource 210 collapses, this stage of the game ends.

211
• We do not tell you how many rounds you will play.

212
• The fish reproduction depends on how much fish there is left on the fish stock and if the climate event occurs or 213 not <point to illustration and remind them of the tables they got> 214 • You are not allowed to show each other what you write down on your decision cards.

215
• Remember, you are allowed to talk in the game. This means you can talk about whatever you want even of how 216 much you want to fish for a maximum of 2 minutes time between rounds. After the 2 minutes, you need to write 217 down your decision.

218
The only difference is that -a climate event did happen and from now on the resource reproduction is lower if the 219 population size is below 28 fish.

221
If not, let's keep playing. The fishing ground restarts with 50 fish, now you have 2 minutes that you could use to discuss 222 your decisions. After that time you need to write your decision and we will pick up the decision folders. size, which is […<write down the stock size for next round>]. We also want to inform you that a climate event -with 227 long lasting and negative consequences for the fishing ground you manage in common might occur.

228
These kinds of climate events are highly unpredictable. This means that you do not know whether and when this event 229 will happen. It could happen in the next round, in four rounds, -or never… 230 In case the event does happen, -the reproduction of fish will reduce below a stock size of 28, -as you can see here <put 231 up visualization of threshold stock dynamics> reproduction will be only 1 for stock sizes between 227. Reproduction 232 stays the same for stock sizes between 28 and 34 (it will be 10) and between 35 and 45 (it will be 5), as you can see 233 here <point to it>. And for stock sizes between 04 and 4550, do not reproduce.

234
Thus, the climate event brings an abrupt reduction on the fish growth if the population size is 28 fish or less. <if 235 participants ask why: the climate event can reduce rain showers, increase water temperature and the risk of droughts. 236 These events impact nutrient availability for fish and the fish reproduction as well as other species in the ecosystem on 237 which fish depends> 238 The assistant will hand out a new table showing the relationship between population size and the reproduction after the 239 climate event <hand out>. 240 We also do not know whether and when this event might happen. I will now tell you how we will determine in which 241 round the event will happen: 242 We have here two bowls -one with 5 green and the other one with 5 red <point out> balls in it. The red ball represents 243 the climate event, the green one means nothing changes -reproduction stays the same. We will now take 1 white and 244 1 red balls <mix in the third nontransparent urn> and then [name of person] will take out 8 of the remaining balls from 245 this bowl, in which we mixed the remaining green and red balls. However, (s)he will do this under the cover of a cloth -246 so we all won't know the amount of white and red balls among the four balls that (s)he picks. < hold a cloth over both 247 urns so that everyone can see that (s)he takes out balls and also how many but neither we nor the participants can see 248 the color>. So now we have here an urn with 10 balls with 1 white, 1 red and 8 balls of which color is uncertain both 249 for you and us.

250
At the beginning of each new round -before you make your decisions -from now on, [assistant name] will draw a ball 251 -but without any of you seeing the color of the ball (s)he draws -If (s)he draws a green ball, nothing will change in that 252 round. But if (s)he will draw the red ball, the climate event will happen. This means we would then calculate the stock 253 size according to the new relation between stock size and reproduction <point to the table again>. 254 As I mentioned before, the event is long lasting. This means, once we drew a red ball, the new relation between stock 255 size and reproduction will apply until the end of the game. Please note, however, that regardless whether we draw a 256 red ball or not, we will continue drawing. Remember -the occurrence of the event is unpredictable and we also do not 257 know whether and when it will happen.

258
With the introduction of this information, we will also reset the stock size to 50 <here please strikethrough the number 259 of fish left last round of the first stage and clarify that the stock size starts again with 50 fish>, like in the beginning of 260 the game. All other rules remain exactly the same:

261
• The four of you share together a fishing ground.

262
• In each round, you will take an individual and private decision of how many fish to catch.

263
• You can choose to fish as much fish as there is available or not fishing at all (zero). For each fish you capture 264 you earn 500 pesos. You will also guess how many fish will be left in the stock for the next round.

265
• Your decisions affect your individual earnings but also the resource of the community.

266
• As long as there is fish left, this stage of the game continues and you can keep earning money. If the resource 267 collapses, this stage of the game ends.

268
• We do not tell you how many rounds you will play.  The only difference is that -a climate event could happen in the following rounds. Now we are going to play the second stage of the game. In this round, we want to inform you about the new stock 285 size, which is […]<write down the stock size for next round>. We also want to inform you that a climate event -with 286 long lasting and negative consequences for the fishing ground you manage in common can occur.

287
These kinds of climate events are highly unpredictable. This means that you do not know whether and when this event 288 will happen. It could happen in the next round, in four rounds, -or never… 289 In case the event does happen, -the reproduction of fish will reduce below a stock size of 28 fish, -as you can 290 see here <put up visualization of threshold stock dynamics> reproduction will be only 1 for stock sizes between 227.

291
Reproduction stays the same for stock sizes between 28 and 34 (it will be 10) and between 35 and 45 (it will be 5), as 292 you can see here . And for stock sizes between 04 and 4550, do not reproduce.

293
Thus, the climate event brings an abrupt reduction on the fish growth if the population size is 28 fish or less. <if 294 participants ask why: the climate event can reduce rain showers, increase water temperature and the risk of droughts. 295 These events impact nutrient availability for fish and the fish reproduction as well as other species in the ecosystem on 296 which fish depends> 297 The assistant will hand out a new table showing the relationship between population size and the reproduction after the 298 climate event <hand out>. 299 We also do not know whether and when this event might happen. I will now tell you how we will determine in which 300 round the event will happen: 301 We have here two bowls -one with 5 green and the other one with 5 red <point out> balls in it. The red ball represents 302 the climate event, the green one means nothing changes -reproduction stays the same. [Name of person] will take 303 the 10 balls (5 green and 5 red) and mix them on the bowl. At the beginning of each new round -before you make your 304 decisions -from now on, [assistant name] will draw a ball -but without any of you seeing the color of the ball (s)he 305 draws -If (s)he draws a green ball, nothing will change in that round. But if (s)he will draw the red ball, the climate 306 event will happen. This means we would then calculate the stock size according to the new relation between stock size 307 and reproduction <point to the table again>. 308 As I mentioned before, the event is long lasting. This means, once we drew a red ball, the new relation between stock 309 size and reproduction will apply until the end of the game. Please note, however, that regardless whether we draw a 310 red ball or not, we will continue drawing. Remember -the occurrence of the event is unpredictable and we also do not 311 know whether and when it will happen. But we both know the probability is 5050.

312
With this new information, we will also reset the stock size to 50 <here please strikethrough the number of fish left last 313 round of the first stage and clarify that the stock size starts again with 50 fish>, like in the beginning of the game. All 314 other rules remain exactly the same:

315
• The four of you share together a fishing ground.

316
• In each round, you will take an individual and private decision of how many fish to catch. You can choose to fish 317 as much fish as there is available or not fishing at all (zero). For each fish you capture you earn 500 pesos. You 318 will also guess how many fish will be left in the stock for the next round.

319
• Your decisions affect your individual earnings but also the resource of the community.

320
• As long as there is fish left, this stage of the game continues and you can keep earning money. If the resource 321 collapses, this stage of the game ends.

322
• We do not tell you how many rounds you will play. The only difference is that -a climate event could happen in the following rounds. If not, let's keep playing. The fishing ground restarts with 50 fish, now you have 2 minutes that you could use to discuss 332 your decisions. After that time you need to write your decision and we will pick up the decision folders. year and the fish stock recover more than normal. The stock size is 50 fish <here please strikethrough the number of 341 fish left last round of the first stage and clarify that the stock size starts again with 50 fish>, like in the beginning of the 342 game. All other rules remain exactly the same:

343
• The four of you share together a fishing ground.
• In each round, you will take an individual and private decision of how many fish to catch. You can choose to fish 345 as much fish as there is available or not fishing at all (zero). For each fish you capture you earn 500 pesos. You 346 will also guess how many fish will be left in the stock for the next round.

347
• Your decisions affect your individual earnings but also the resource of the community.

348
• As long as there is fish left, this stage of the game continues and you can keep earning money. If the resource 349 collapses, this stage of the game ends.

350
• We do not tell you how many rounds you will play.

357
The only difference is that -a positive event made that the stock size grew more than normal and we start with 50 fish 358 again.         (1) mean extraction, (2) mean proportion of extraction, (3) median cooperation, (4) variance of cooperation, (5) variance of extraction, (6) variance of the proportion of extraction, and (7) coordination.

Dependent variable:
(1) Clustered robust standard errors and confidence intervals were calculated with the CR2 estimator.